TW202338482A - Ultrasonic imaging device with programmable anatomy and flow imaging - Google Patents

Abstract

An imaging device includes a transducer that includes an array of piezoelectric elements formed on a substrate. Each piezoelectric element includes at least one membrane suspended from the substrate, at least one bottom electrode disposed on the membrane, at least one piezoelectric layer disposed on the bottom electrode, and at least one top electrode disposed on the at least one piezoelectric layer. Adjacent piezoelectric elements are configured to be isolated acoustically from each other. The device is utilized to measure flow or flow along with imaging anatomy.

Description

Ultrasound imaging device with programmable anatomy and flow imaging

The present invention relates to imaging devices and, more particularly, to portable handheld ultrasound imaging devices having the capability to perform flow and anatomical imaging.

The transducer in an ultrasound imager sends an ultrasound beam toward the target to be imaged and uses the signal from the reflected waveform to create the image. Reflected waveforms from tissue are used to form an image of the anatomy being viewed, while blood flow, velocity and direction are measured using Doppler shift principles under electronic control.

One specific embodiment is related to an imaging device, including: a transducer, the transducer includes an array of piezoelectric elements formed on a substrate, each piezoelectric element includes: at least one layer of film, and at least one layer of film is suspended relative to the substrate; at least one bottom electrode, at least one bottom electrode disposed on the membrane; at least one piezoelectric layer, at least one piezoelectric layer disposed on the bottom electrode; and at least one top electrode, at least one top electrode disposed on the at least one piezoelectric layer, Adjacent piezoelectric elements are acoustically isolated from each other.

Ultrasound imaging (ultrasound) uses high-frequency sound waves to see inside the body. Because ultrasound images are taken in real time, they can also show the movement of the body's internal organs and the blood flowing through blood vessels. Sound waves are used to create and display images of the internal structures of the human body, such as tendons, muscles, joints, blood vessels, and internal organs.

To perform imaging, the imaging device sends signals into the body and receives reflected signals from the body part being imaged. Types of imaging devices include transducers, which may also be called transceivers or imagers, and may be based on photoacoustic or ultrasonic effects. Such transducers could be used in imaging as well as other applications. For example, transducers can be used in medical imaging to view the anatomy of tissues or other organs in the human body. The transducers can also be used in industrial applications such as materials testing or therapeutic applications such as localized tissue heating for HIFU-based surgery. Doppler measurement techniques are used when imaging a target and measuring its motion (such as flow rate and direction of blood). Doppler technology is also used in industrial applications to measure flow rates, such as fluid or gas flow in pipes.

The difference between the frequency of the transmitted wave and the frequency of the reflected wave due to the relative motion between the source and the object is called the Doppler effect. The frequency shift is proportional to the speed of movement between the transducer and the object. This effect is exploited in ultrasound imaging to determine blood flow velocity and direction.

Doppler imagers can produce continuous wave (CW) or pulsed wave (PW) ultrasound beams. In continuous wave Doppler, the signal is transmitted and received continuously, requiring two element transducers, one for transmitting and the other for receiving. In PW operation, a single-element transducer is used to send and receive ultrasonic signals.

For ultrasound imaging, a transducer is used to transmit an ultrasound beam toward the target to be imaged. The transducer receives the reflected waveform, converts it into an electrical signal, and uses further signal processing to create an image. Velocity and flow direction can be measured using micromachined ultrasonic transducer (MUT) arrays.

B-mode imaging for anatomy is a two-dimensional ultrasound image display consisting of dots representing ultrasound echoes. The brightness of each point is determined by the amplitude of the returned echo signal. This allows visualization and quantification of anatomical structures, as well as visualization of diagnostic and therapeutic procedures. Typically, the B-mode image closely resembles the actual anatomy of the cropped view on the same plane. In B-mode imaging, the transducer is first placed in transmit mode and then in receive mode to receive echoes from the target. The echoes are signal processed into an anatomical image. The transducer elements are programmable so they can be in transmit mode or receive mode, but not both at the same time.

Using color Doppler, color Doppler imaging (or simply color Doppler) allows visualization of the direction and velocity of blood flow in an artery or vein within a user-defined area. A region of interest is defined and the Doppler shift of the returned ultrasound waves is color-coded according to mean velocity and direction. Sometimes these images are overlapped (co-imaged) with anatomical images in B-mode scans to present a more intuitive sense of flow relative to the anatomy being viewed. Doppler imaging can also be PW Doppler imaging, so the range and velocity of the flow rate can be determined, but the maximum flow rate depends on the pulse repetition frequency used, otherwise the image will be aliased, making higher velocities Looks like lower speed. The Doppler shift can be measured from the collection of received waves using the PW mode of Doppler imaging to measure flow velocity. CW Doppler is a continuous imaging technique that avoids aliasing by continuously transmitting from one transducer element while receiving echoes from another transducer element. Using this technique, the range is undefined. In programmable instruments, both pulsed and continuous techniques can be used. PW and Color Doppler can use a selected number of elements in the array. First, the element is placed in transmit mode, and after the echo returns, the element is placed in receive mode, where the received signal is processed for Doppler signal imaging. For continuous wave Doppler, at least two different elements are used, with each element continuously in transmit mode and the other element continuously in receive mode.

Doppler signals from moving objects not only contain information about flow, but also backscatter signals, which contain clutter from surrounding tissue or slow-moving blood vessels. This clutter signal is typically 40 to 80 dB stronger than the Doppler shifted signal originating from blood. Therefore, clutter suppression is required to accurately estimate flow rates. Clutter suppression is a step in processing Doppler signals. A high pass filter (HPF) can be used to remove clutter signals from Doppler shifted signals. High-pass filters are used to suppress signals from stationary or slow-moving tissue or any other organ. Signals from slow-moving objects are low-frequency signals, but their amplitudes can be much stronger than high-frequency signals generated from faster blood flow. Therefore, to separate the signal from blood and tissue, a high-pass filter with a steep transition band is used. These filters can be developed digitally in the receiver. These filters, sometimes called wall filters, are used to observe differences in signals from different transmissions and align their signals with the same phase. Any deviation caused by Doppler shift is the desired output. However, if low-frequency clutter causes this deviation, the sensitivity of the flow detection algorithm will be reduced. The effects of switching-mode DC-to-DC converter-based power supplies can cause clock frequencies and harmonics to appear in the power supply. Furthermore, these frequencies can give rise to other frequencies due to the interaction of other switching phenomena, such as the pulse repetition rate of the Doppler sequence.

To the extent that these behaviors or intermodulation behaviors are caused by nonlinearities, spurious signals can appear in the frequencies of interest for flow imaging, thereby reducing the sensitivity of flow imaging. Another example of clutter is the amplitude jitter of the pulses used in transmitting pulses. One source of clutter can be differences in supply amplitude between pulses because the supply capacitor is drained of charge during the pulse to deliver current and is not charged to the same level on the next pulse.

In addition to using a digital wall filter, low-frequency components that cause clutter can be minimized by using a high-pass filter before the digital filter. Filters can be in the analog domain or in the digital domain. Parts of these filters can also be implemented on the transducer interface, allowing real-time control of the high-pass frequency by controlling the radio frequency (R _f ) and carrier frequency (C _HF ) networks. Radio frequency (R _f ) refers to the rate at which electromagnetic waves oscillate in the range 3 kHz to 300 GHz, as well as the rate at which alternating current carries radio signals. Carrier frequency (C _HF ) is defined as the transmission of a fixed frequency that has been altered or modulated to carry data. This achieves a high-pass slope of 20dB/Dec.

Additionally, in addition to using low-noise amplifiers (LNAs), other digitally controlled high-pass filters (HPFs) can be utilized to simplify operation in the receiver, thereby saving power and processing time. By eliminating unnecessary noise before time gain compensation (TGC), the LNA can increase the dynamic range of the signal provided to the analog-to-digital converter (ADC). The digitized bits can now be processed for further Doppler operations.

Doppler acquisition relies on repeated transmission of pulses to acquire data from a specific region of interest. Such acquisition is precise in its period to ensure uniform sampling of the Doppler signal for further spectrogram processing. This can be a major limitation of ultrasound imaging systems when Doppler signal acquisition is done in duplex or triple imaging modes (where B-mode or color flow signals are acquired simultaneously). This limitation reduces the frame rate of other modes and therefore limits the sonographer's ability to track events in real time. Furthermore, rapid and periodic transmission of ultrasonic pulses to the same location increases the average power per unit area beyond certain safety standards, so limits on the generated acoustic power prompt close attention to keeping it within the safety zone.

The Doppler shift principle is used to calculate blood flow velocity. Other types of velocities can be calculated, such as body fluids, industrial fluids, gases, etc. As the observer moves toward the source, the frequency increases fr due to the transmission of more sound wave cycles per second. The formula for _r is: _fr = f _t

In the above, _ft is the transmitting frequency, c is the speed of sound in the tissue, and v is the speed of the observer (e.g. blood).

If the observer's velocity is at an angle ø to the direction of wave propagation, the velocity is replaced by the velocity component v cosø in the direction of the wave. f _ry = f _t

If the observer is at rest and the source moves with some speed in the direction of wave propagation, the wavelength will be compressed. The resulting observed frequency is: f _ry = f _t

Consider the angle: f _ry = f _t

In ultrasound applications, the ultrasound beam is backscattered from moving blood cells and tissue. The above two effects combine to shift the transmitted Doppler frequency. The observed frequency is then given by: f _ry = f _t * = f _t

As mentioned above, the Doppler shift frequency is the difference between the incident frequency f _t and the reflected frequency f _r , and is therefore given by: f _d = f _{r -} f _t f _d = f _t - f _t

Since c >> v f _d =

From the last relationship, the Doppler shift depends on the angle with the direction of propagation and the transmit frequency.

Optimal reflection occurs when measured at 90 degrees to electronically controlled azimuth and elevation angles for optimal Doppler signal detection. This elevation steering is controlled by a combination of elevation delay control and any desired azimuth angle.

A continuous wave Doppler system is a system that sends and receives continuous ultrasound waves by using two separate transducer elements housed within the same probe. Because transmit and receive are continuous, the system has no depth resolution unless the signal from a close transducer is less attenuated than from a distant target. The transmit beam 2112 and the receive beam 2114 are shown in Doppler sample volumes in Figure 24. The flow-sensitive area 2116 (sampling volume) over which Doppler information can be acquired is the area where the transmit and receive beams overlap, as shown by the cross-hatching at a distance from the transducer face.

For example, you can construct an element that contains two sub-elements, one of which can be in transmit mode and the other in receive mode. By using embedded twin elements rather than individual elements within the transducer, the entire transducer area or selected portions thereof can be used for both transmission and reception. Likewise, the intersection area is increased by using double subcomponents.

Imaging devices such as ultrasound imagers used in medical imaging use piezoelectric (PZT) materials or other piezoelectric ceramic and polymer composites. To make bulk PZT elements for use in transducers, thick sheets of piezoelectric material can be cut into large rectangular PZT elements. Rectangular PZT elements are expensive to manufacture because the manufacturing process involves precisely cutting rectangles of thick PZT or ceramic material and mounting them to a substrate at precise spacing. Additionally, the impedance of the transducer is much higher than the acoustic impedance of the tissue, which requires the use of impedance matching layers to allow actual signal transmission and reception.

Furthermore, such thick bulk PZT components may require relatively high voltage pulses. For example, 100 volts (V) or more may be required to generate a transmission signal. High drive voltage results in high power dissipation because the power dissipated in the transducer is proportional to the square of the drive voltage. High power dissipation generates heat within the imaging device, thus requiring cooling devices. The use of a cooling system increases the manufacturing cost and weight of the imaging device, which makes the imaging device more burdensome to operate. High voltage also increases the cost of electronic devices.

Furthermore, the transmit/receive electronics for the transducer may be located remotely from the transducer itself, thus requiring a micro coaxial cable between the transducer and the transmit/receive electronics. Typically, cables are of precise length for delay and impedance matching, and additional impedance matching networks are often used to effectively connect the transducer to the electronic components through the cable.

Accordingly, this specification describes the use of piezoelectric micromachined ultrasound transducers (pMUTs) that can be efficiently formed on a substrate using various semiconductor wafer fabrication operations. Semiconductor wafers may be available in sizes of 6 inches, 8 inches, and 12 inches, and can accommodate hundreds of transducer arrays. These semiconductor wafers start with a silicon substrate on which various processing steps are performed. An example of such an operation is the formation of a SiO2 layer, also known as an insulating oxide. Various other steps can be used, such as adding metal layers to serve as interconnects and bonding pads or copper pillars to allow the pMUT to be bonded to other electronic components. Furthermore, using etching techniques to create cavities in silicon structures allows the formation of membranes that can move under electrical control or due to external pressure input. Compared with traditional transducers with bulky piezoelectric materials, pMUTs built on semiconductor substrates are smaller, cheaper to manufacture, simpler to interconnect between electronic components and transducers, and more efficient. As a result, they offer flexibility in operating frequency and the potential to generate higher quality images due to lower parasitics in the interconnect.

In one example, the imaging device is coupled to an application specific integrated circuit (ASIC) that includes a transmit driver, sensing circuitry for received echo signals, and control circuitry to control various operations. The ASIC can be formed on a separate semiconductor wafer, while the pMUT can be formed on another wafer. Likewise, the ASIC can be placed in close proximity to the pMUT components to reduce parasitic losses. In one example, the ASIC may be 50 micrometers (μm) or less away from the transducer array. The spacing between 2 wafers or 2 dies may be less than 100 µm where each wafer contains many dies and the die contains a transducer in a transducer wafer and in an ASIC wafer Contains an ASIC. The ASIC may have matched dimensions relative to the pMUT to allow stacking of devices for wafer-to-wafer interconnection, or transducer wafer on ASIC wafer, or transducer wafer-to-ASIC wafer interconnection. Alternatively, the transducer can be developed on top of the ASIC wafer using low-temperature piezoelectric material sputtering and other low-temperature processes that are compatible with ASIC processing.

Although pMUTs have potential for advanced ultrasound imaging, certain limitations limit their utilization in high-performance imaging implementations. For example, pMUTs utilizing aluminum nitride exhibit low sensitivity associated with transmit and receive operations, making them candidates for less demanding applications. Other pMUTs utilizing PZT require relatively high voltages and have relatively low bandwidth and low efficiency.

Therefore, the pMUT described in this specification: 1) has enhanced sensitivity; 2) can operate at low voltages; 3) exhibits high bandwidth operation; and 4) exhibits good linearity. In particular, this specification describes pMUTs closely associated with associated control circuitry. This allows 2D and 3D imaging under the control of control circuitry in small portable devices.

Another type of transducer is the capacitive micromachined ultrasound transducer (cMUT). However, compared to PZT-based devices, cMUT sensors struggle to generate sufficient sound pressure at lower frequencies (where much deep medical imaging occurs) and are inherently nonlinear. In addition, cMUT requires high voltage operation.

Generally, the imaging device of this specification includes a plurality of transmitting channels and a plurality of receiving channels. The sending channel drives the piezoelectric element with a voltage pulse, and the frequency of the piezoelectric pulse is the frequency at which the piezoelectric element responds. This results in an ultrasound waveform being sent from the piezoelectric element, which is directed towards the object to be imaged. In some examples, an imaging device having a transducer array of piezoelectric elements is in mechanical contact with the body using a gel between the imaging device and the body. The ultrasound waveform propagates towards the object (i.e. organ) and a portion of the waveform is reflected back to the piezoelectric element, where the received ultrasound energy is converted into electrical energy and further processed through multiple receiving channels and other circuits to visualize the object. images.

These transmit and receive channels consume power, and in instruments with many channels (to produce high-quality images), the power can cause excessive heat in the imaging device. If the temperature rises above a certain value, it may affect the operation of the imaging device, may cause danger to the operator, may cause danger to the patient, and may exceed regulatory requirements limiting temperature increases. Ultrasound imaging devices include transducer arrays, ASICs, transmit and receive beamforming circuits, and control electronics. Specifications limit the maximum allowable temperature, which in turn severely limits the electronic circuitry that can be accommodated in the imaging device, and also limits how the imaging device can operate. Such limitations may have a negative impact on the obtained image quality and frame rate of the image. Additionally, the imaging device may be battery powered, which may rapidly drain power in instruments with multiple channels as each channel consumes energy.

The imaging device disclosed in this article addresses these and other issues. Specifically, the imaging device controls power consumption without exceeding temperature limits of the imaging device while maintaining desired image quality. In particular, the number of receive channels and/or transmit channels used to form the image is electronically adaptable to save power, for example, where a smaller number of channels is acceptable. As a specific example, each of multiple channels can be dynamically controlled to reduce power or power down completely. Additionally, other features of each channel can be configured to reduce power consumption. This advanced control allows the imaging device to operate within safe temperature thresholds and without substantially sacrificing required image quality. Lower power consumption also extends battery life.

Furthermore, the imaging device includes a handheld housing in which the transducer and associated electronics are housed. The imaging device may also include batteries to power electronic components. As described above, the power consumed by the imaging device increases the temperature of the imaging device. To ensure satisfactory use and performance of the imaging device, the temperature of the imaging device body should be maintained below a threshold temperature. Obtaining high quality images consumes significant power, reduces battery life, and increases probe temperature, however the imaging device of this specification is electronically configured to reduce power and temperature.

In one example, this disclosure describes a high-performance, low-power, and low-cost portable imaging device capable of 2D and 3D imaging using pMUTs in a 2D array built on a silicon wafer. Such arrays, configured electronically with certain parameters, coupled to ASICs, enable higher quality image processing at a lower cost than was previously possible. By controlling certain parameters, such as the number of channels used or the amount of power used by each channel, you can change the power consumption and change the temperature.

This disclosure describes an imaging device that relies on a pMUT-based transducer that is coupled to control electronics on a per-pixel basis and housed in a portable housing. The imaging device allows for real-time system configurability and adaptability to proactively control power consumption and temperature in the imaging device. Specifically, flow imaging consumes more power than anatomical imaging modes. Power consumption is reduced by minimizing power consumption within the imaging device by 1) changing the aperture size and/or 2) actively controlling power consumption in these channels so that the temperature within the imaging device does not exceed specification limits. All other functions can be achieved while achieving excellent performance. Additionally, acoustic power output can be increased in Doppler mode compared to other anatomical modes. Electronic means are provided to control this power output level.

The manufacturing costs of the pMUTs described in this article can be reduced by applying modern semiconductor and wafer processing technologies. For example, a thin-film piezoelectric layer can be spun or sputtered on a semiconductor wafer and then patterned to create piezoelectric sensors, each with two or more electrodes. In one example, each piezoelectric element may be designed with the ability to transmit or receive signals at a specific frequency (called a center frequency) as well as a second and/or additional frequency. Note that the terms piezoelectric element, pMUT, transceiver and pixel are used interchangeably in this article.

In one example, an imaging device includes a transducer having an array of piezoelectric elements formed on a substrate. Each piezoelectric element includes: at least one membrane suspended relative to the substrate; at least one bottom electrode disposed on the membrane; at least one piezoelectric layer disposed on the bottom electrode; and at least one piezoelectric layer disposed on at least one piezoelectric layer. Top electrode. Adjacent piezoelectric elements are configured to be acoustically isolated from each other.

In another example, an imaging device includes a transducer having a two-dimensional (2D) array of piezoelectric elements arranged in rows and columns on the transducer. Each piezoelectric element has at least two terminals and is physically isolated from each adjacent piezoelectric element to minimize crosstalk. A first group of piezoelectric elements of the array includes each piezoelectric element having a first top electrode connected to a corresponding receive amplifier and electronically programmed to appear to be connected together to form a first row. The second set of piezoelectric elements of the array includes each piezoelectric element having a second top electrode connected to a corresponding transmit driver and electronically programmed to appear to be connected together to form a second row.

In another example, an imaging device includes a transducer and a 2D array of piezoelectric elements arranged in rows and columns on the transducer. Each piezoelectric element has at least two terminals. At least a first row of piezoelectric elements includes each piezoelectric element having a first top electrode coupled to a corresponding receive amplifier or transmit driver under programmed control. At least a second row of piezoelectric elements includes each piezoelectric element having a first top electrode coupled to a corresponding receive amplifier or transmit driver under programmed control. Piezoelectric elements are programmed to transmit first and then receive, or to transmit and receive simultaneously.

Turning now to the drawings, Figure 1 shows a block diagram of an imaging device (100) having transmit (106) and receive channels (108) controlled by a control circuit (109) and having a computing device Imaging calculations performed on (110). Figure 1 also includes a power supply (111) to power various components in the imaging device (100).

As mentioned above, the imaging device (100) may be used to generate images of internal tissue, bones, blood flow, or organs within a human or animal body. Thus, the imaging device (100) transmits signals into the body and receives reflected signals from the body part being imaged. Such an imaging device (100) includes a piezoelectric transducer (102), which may be referred to as a transceiver or imager that may be based on photoacoustic or ultrasonic effects. The imaging device (100) may also be used to image other objects. For example, the imaging device (100) may be used for medical imaging, for flow measurement of fluids or gases in pipelines, lithotripsy, and local tissue heating for therapeutic and high-intensity focused ultrasound (HIFU) procedures.

In addition to use with human patients, the imaging device (100) may be used to obtain images of the internal organs of animals. Furthermore, in addition to imaging internal organs, the imaging device (100) may be used to determine the direction and velocity of blood flow in arteries and veins and tissue stiffness through Doppler mode imaging.

The imaging device (100) can be used to perform different types of imaging. For example, the imaging device (100) may be used to perform one-dimensional imaging (also known as an A-scan), 2D imaging (also known as a B-scan (B-mode)), three-dimensional (3D) imaging (also known as a C-scan), and Doppler imaging. The imaging device (100) can be switched to different imaging modes and can be electronically configured under program control.

To facilitate such imaging, the imaging device (100) includes an array of piezoelectric transducers (102), each piezoelectric transducer (102) including an array of piezoelectric elements (104). The piezoelectric element (104) may also include two or more sub-elements, each of which may be configured in transmit or receive operations. The piezoelectric element (104) does the following: 1) generates pressure waves that pass through the human body or other objects, and 2) receives reflected waves that are imaged by objects in the human body or other objects.

In some examples, imaging device (100) may be configured to transmit and receive ultrasound waveforms simultaneously. For example, some piezoelectric elements (104) may send pressure waves toward the target object being imaged, while other piezoelectric elements (104) receive pressure waves reflected from the target object and generate a charge in response to the received waves.

In some examples, each piezoelectric element (104) can send or receive signals at a known frequency (called a center frequency) as well as second and/or additional frequencies. Such a multi-frequency piezoelectric element (104) may be called a multi-modal piezoelectric element (104), and may expand the bandwidth of the imaging device (100).

The piezoelectric material forming the piezoelectric element (104) contracts and expands when different voltage values of a certain frequency are applied. Thus, as the voltage alternates between different applied values, the piezoelectric element (104) converts electrical energy (i.e., voltage) into mechanical motion, thereby producing sound energy, which is sent in the form of a wave at the desired frequency. These waves are reflected from the target being imaged and received at the same piezoelectric element (104) and converted into electrical signals which are then used to form an image of the target.

To generate pressure waves, the imaging device (100) includes a plurality of transmit channels (106) and a plurality of receive channels (108). The transmission channel (106) includes a plurality of components that drive the transducer (102) (ie, the array of piezoelectric elements (104)) with voltage pulses at a frequency to which they respond. This causes an ultrasound waveform to be sent from the piezoelectric element (104) towards the object to be imaged. The ultrasonic waveform travels towards the object to be imaged and part of the waveform is reflected back to the transducer (102) where the reflected waveform is collected at the receiver (108), converted to electrical energy and processed for e.g. A displayable image is developed at the computing device (110).

In some examples, while the number of transmit channels (106) and receive channels (108) in the imaging device (100) remains constant, the number of piezoelectric elements (104) to which they are coupled can vary. This coupling is controlled by the control circuit (109). In some examples, portions of control circuitry (109) may be distributed among transmit channels (106) and receive channels (108). For example, the piezoelectric elements (104) of the transducer (102) may be formed as a 2D array with N rows and M columns.

In one example, the 2D array of piezoelectric elements (104) has a number of columns and rows, such as 128 rows and 32 columns. The imaging device (100) may have up to 128 transmit channels (106) and up to 128 receive channels (108). Each transmit channel (106) and receive channel (108) is coupled to multiple or a single piezoelectric element or sub-element (104). Depending on the imaging mode, each column of piezoelectric elements (104) may be coupled to a single transmit channel (106) and a single receive channel (108). The transmit channel (106) and the receive channel (108) receive composite signals that combine the signals received at each piezoelectric element (104) within the corresponding row.

In another example, (i.e., during different imaging modes), individual piezoelectric elements (104) are coupled to their own transmit channel (106) and their own receive channel (108).

In other examples, computing device 110 or power supply and battery 111 are external.

Figure 2 is a diagram of an imaging system having flow imaging capabilities as well as anatomical imaging capabilities according to an example of the principles described herein. As depicted, the imaging system includes an imaging device (100) that generates and transmits pressure waves (106) to an internal organ, such as the heart (214), in a transmit mode/process via a transmit channel (Fig. 1: 106). 210). Internal organs or other objects to be imaged can reflect part of the pressure wave (210) to the imaging device (100), and the imaging device (100) captures the receiving channel (Fig. 1:108) through the transducer (Fig. 1:102), Control circuitry (Fig. 1:109), computing device (Fig. 1:110) and reflect the pressure wave and generate electrical signals in the receive mode/processing. The system also includes another computing device (216) in communication with the imaging device (100) via the communication channel (218). The imaging device (100) may transmit electrical signals to a computing device (216), which processes the received signals to complete formation of an image of the object. The system's display device (220) may then display images of the organ or target, including images showing images related to blood flow in the target area.

As shown in Figure 2, the imaging device (100) may be a portable handheld device that communicates wirelessly (using a protocol such as the 802.11 protocol) or via a cable (eg, Universal Serial Bus 2 (USB2)) over a communication channel (218) , USB 3, USB 3.1, and USB-C) to communicate signals with the computing device (216). In the case of a tethered connection, the imaging device (100) may include a port as shown in Figure 3 for receiving a cable to communicate with the computing device (216). In the case of a wireless connection, the imaging device (100) includes a wireless transmitter for communicating with the computing device (216).

As shown, the display device (220) and computing device (216) may be separate from the imaging device (100). For example, computing device (216) and display device (220) may be disposed within a separate device (eg, a mobile device such as a cellular phone or an iPad or a stationary computing device) that can display images to a user. In another example, display device (220) and computing device (220) are included within imaging device (100). That is, the imaging device (100), computing device (216) and display device (220) are arranged within a single housing.

Figure 3 is a schematic diagram of an imaging device (100) with flow and anatomical measurement capabilities according to an example of the principles described herein. As mentioned above, the imaging device (100) may be an ultrasound medical probe. Figure 3 depicts the transducer (102) of the imaging device (100). As mentioned above, the transducer (102) includes an array of piezoelectric elements (Fig. 1:104) that transmit and receive pressure waves (Fig. 2:210). In some examples, imaging device (100) includes coating (322) that serves as an impedance matching interface between transducer (102) and the human body or other objects through which pressure waves propagate (Figure 2 :210) is transmitted. In some cases, when the coating (322) is designed to have a curvature consistent with the desired focal length, it can function as an impedance matching layer and can also function as a lens. The coating (322) may be composed of several layers of material, some of which are used to impedance match the transducer to tissue acoustic impedance, and some of which are shaped into mechanical lenses to focus the acoustic signal in the elevation direction.

In embodiments, the user can apply the gel on the human body's skin before direct contact with the coating (322), thereby improving the impedance matching at the interface between the coating (322) and the human body. Impedance matching reduces the loss of pressure waves (Fig. 2: 210) at the interface and the loss of reflected waves propagating toward the imaging device (100) at the interface.

In some examples, coating (322) may be a flat layer to maximize transmission of acoustic signals from transducer (102) to the human body and vice versa. Certain portions of the coating (322) may be one quarter wavelength thick at a certain frequency of the pressure wave (Fig. 2: 210) generated or received by the transducer (102).

The imaging device also includes control circuitry (109), such as an ASIC, for controlling the transducer (102). Control circuitry (109) may be housed in the ASIC along with other circuitry coupled to the transducer (102) through bumps connecting the transducer (102) to the ASIC. As mentioned above, the transmit channels (106) and receive channels (108) can be selectively changed, which means that the number of transmit channels (106) and receive channels (108) activated at a given time can be changed, thereby powering the transmit channels The consumption characteristics and functionality of (106) and receive channel (108) can be changed. For example, if it is desired to vary the acoustic power during flow imaging mode, this can be achieved by electronically controlling the transmission channel relative to the number of elements to be used on the line or the aperture to be used.

The sending driving signal can be a multi-level signal, such as 5V, 0V and -5V. Other examples include 15V, 0V and -15V. Other values are also possible. The signal can consist of many pulses or be continuous at the desired frequency. Drivers on the transmitter convert these multi-level signals, initially encoded as digital binary bits, into a final output level, such as 15V. Using many of these channels, an ultrasound transmission beam is created. By controlling the delay in the channel, the beam can be controlled in two or three dimensions. 3D beamforming is possible using various beamforming operations described in this article. Enable this feature using a 2D array addressable in the X and Y axes. Biplane imaging is also possible.

The imaging device (100) may further include a field programmable gate array (FPGA) or a graphics processing unit (GPU) (326) for controlling components of the imaging device (100); circuitry (328) such as an analog front end (AFE) ) for processing/conditioning the signal; and an acoustic absorbing layer (330) for absorbing waves generated by the transducer (102) and propagated to the circuit (328). For use with the acoustic absorbing layer (330), the transducer (102) can be mounted on a substrate and can be attached to the acoustic absorbing layer (330). Make the layer absorb any ultrasound signals sent in the opposite direction, which might otherwise be reflected and interfere with image quality. Although Figure 3 depicts an acoustic absorbing layer (330), this component may be omitted in the event that other components prevent transmission of ultrasound waves backward (ie, away from the transducer (102)) through the material. Acoustic absorbers may also be embedded between 102 and 109.

The imaging device (100) may include a communication unit (332) for communicating data with external devices such as computing and display devices, such as a smartphone or tablet (Fig. 2, 216). Communication may occur, for example, via port (334) or a wireless transmitter. The imaging device (100) may include memory (336) for storing material. In some examples, imaging device (100) includes a battery (338) for providing power to components of imaging device (100). Electronic control of the channels and associated circuitry may have a particularly important impact when the imaging device (100) includes a battery (338). For example, because the receive channel (Figure 1:108) and the transmit channel (Figure 1:106) include components that consume power, the battery will drain over time. In some examples, the power consumption of these components may be so great that the battery (338) will be depleted in a short period of time. This is especially important when a lot of power is consumed to obtain high-quality images. The battery (338) may also include battery charging circuitry, which may be wireless or wired charging circuitry. The imaging device (100) may include a gauge indicating power consumption, and this gauge is used to configure the imaging device (100) to optimize power management to increase battery life.

The ease of use of the imaging device (100) is improved by extending the life of the battery (338) by reducing power consumption or, in some examples, completely turning off power to different channels (Fig. 1: 106, 108). This applies particularly to imagers that support flow imaging, where power consumption is further increased.

Figure 4 is a side view of an example transducer (102) array in accordance with the principles described herein. As mentioned above, the imaging device (Fig. 1, 100) may include an array of transducers (102-1, 102-2, 102-3), each transducer having their own array of piezoelectric elements (Fig. 1, 104 ). In some examples, the transducer (102) may be curved to provide a wider angle of the object to be imaged (Fig. 2, 214). In other examples, the transducer (102) and array are arranged on a flat surface. Figure 5 depicts a top view of the transducer (102) array. As shown in Figure 5, the transducer (102) may include a transceiver substrate (540) and one or more piezoelectric elements (104) disposed thereon. Unlike conventional systems that use bulk piezoelectric elements, the piezoelectric elements (104) can be formed on a wafer. The wafer may be diced to form multiple arrays of transducers (102) for use in constructing imaging devices. This process can reduce manufacturing costs because arrays of multiple transducers (102) in the form of dice can be manufactured in high volumes and at low cost.

In some examples, the diameter of the wafer can range from 6 to 12 inches, and many arrays of transducers (102) can be mass-fabricated thereon. Additionally, in some examples, the control circuitry (Fig. 1, 109) for controlling the piezoelectric elements (104) may be formed such that each piezoelectric element (104) is coupled to a matching integrated circuit (e.g., a receive channel ( Figure 1, 108) and the transmit channel (Figure 1, 106)) are very close, preferably within 25 µm to 100 µm. For example, the transducer (102) may have 1,024 piezoelectric elements (104) and be coupled to a matching control circuit (Fig. 1, 109) with the appropriate number for the 1,024 piezoelectric elements (104) transmitting and receiving circuits.

Each piezoelectric element (104) may have any suitable shape, such as square, rectangular, and circular. As shown in Figure 5, in some examples, piezoelectric elements (104) may be arranged in a two-dimensional array arranged in orthogonal directions. That is, the array of piezoelectric elements (104) may be an MxN array having N rows (542) and M columns (544).

To create a line element, rows (542) of N piezoelectric elements (104) can be effectively electrically linked. This wire element can then provide transmission and reception of ultrasonic signals similar to those achieved by a single bulk piezoelectric element, with each of the two electrodes of each piezoelectric element (104) being electrically linked to achieve N times larger rows than each piezoelectric element (104). This line element is interchangeably called a row or line or line element. An example of a row of piezoelectric elements (104) is shown in Figure 5 by reference numeral (542). In this example, the piezoelectric elements (104) are arranged in row (542) and have associated transmit driver circuits (part of the transmit channel) and low-noise amplifiers (LNA), which are part of the receive channel circuit. Although not explicitly shown, the transmit and receive circuits include multiplexing and address control circuits to enable the use of specific elements and groups of elements. It should be understood that the transducer (102) may be arranged in other shapes, such as circular or other shapes. In some examples, piezoelectric elements (104) may be spaced 250 μm from center to center. It should be noted that since the piezoelectric elements (104) are connected under programming control, for example, the number of piezoelectric elements (104) connected in a row is programmable.

For the transducer (102), the circuit elements can be designed using a plurality of identical piezoelectric elements (104), where each piezoelectric element (104) can have its characteristic center frequency. When a plurality of piezoelectric elements (104) are linked together, a composite structure (ie, a wire element) can be used as a wire element, the center frequency of which consists of the center frequency of all the element pixels. Using modern semiconductor processing for matching transistors, these center frequencies match each other very well and have very small deviations from the center frequencies of the line elements. Instead of just using a line with one center frequency, you can also blend several pixels with slightly different center frequencies to create a broadband line.

In some examples, the ASIC coupled to the transducer (102) may include one or more temperature sensors (546-1, 546-2, 546-3, 546-4) to measure the temperature of the ASIC and the transducer. temperature in the area. Although Figure 5 shows the temperature sensor (546) disposed at a particular location, the temperature sensor (546) may be disposed at other locations on the imaging device (Fig. 1, 100), and additional sensors may be disposed at other locations.

The temperature sensor (546) may be the trigger for selective adjustment of the channels (Fig. 1, 106, 108). That is, as described above, the temperature within the handheld portable imaging device (Fig. 1, 100) may rise above a predetermined temperature. The transducer (102) may be coated with material to serve as an interface between the transducer and the patient contact surface. In one example, the material is used as a backing layer disposed on the ASIC-facing surface of the transducer. The material may be polydimethylsiloxane (PDMS) or other similar material with an acoustic impedance between the transducer and the tissue acoustic impedance level at the tissue frequency of interest. The temperature sensor (546) detects the temperature of the device on the surface of the imager that is in contact with the patient due to its proximity to this area. If the temperature sensor (546) detects a temperature greater than a threshold (e.g., a temperature set by a user or a temperature set by a regulatory agency), the controller (Fig. 3, 324) can close all or some of the sending channels through signaling (Fig. 1, 106) and/or receive channels (Fig. 1, 108), or set all or some of the transmit channels (Fig. 1, 106) and/or receive channels (Fig. 1, 108) to a low power state.

Figure 5 also depicts the terminals of the piezoelectric element (104). Specifically, each piezoelectric element (104) has two terminals. The first terminal is a common terminal shared by all piezoelectric elements (104) in the array. The second terminal connects the piezoelectric element (104) to the transmit channel (Fig. 1, 106) and the receive channel (Fig. 1, 108), where the transmit channel and the receive channel may be located on different substrates. The second terminals are the drive and sense terminals for each piezoelectric element (104), as indicated by the symbols for those piezoelectric elements (104) in the first row. For simplicity, the transmit channel (106) and the receive channel (108 in Figure 1) appear to be linked together. However, in some examples they may be individually controlled to be active in transmit mode, receive mode, or both, and the wiring is more complex than shown here for simplicity. Additionally, for simplicity, the second terminals are indicated only for those piezoelectric elements (104) in the first row. However, similar terminals with associated transmit channels (106) and receive channels (108) populate the other piezoelectric elements (104) in the array. The control circuit (Fig. 1, 109) uses control signals to open the corresponding transmit channel (Fig. 1, 106) and receive channel (Fig. 1, 108) and close the channels (Fig. 1, 106, Fig. 1, 108) in other rows (542). 108), to select the row (542) of the piezoelectric element (104). In a similar manner, it is also possible to turn off specific columns (54), or even individual piezoelectric elements (104).

6A is a perspective view of a scan line (650) of an imaging device (100) and a frame (648) according to an example of principles described herein. A frame (648) refers to a single still image of an organ or other object to be imaged. The plot frame (648) may be a section line through the object. The frame (648) consists of individual scan lines (650). That is, the frame (648) can be thought of as an image, and the scan lines (650) represent a portion of the frame (648) that represents this image. Depending on the resolution, a particular frame (648) may include a varying number of scan lines (650) ranging from less than a hundred to hundreds.

To form the frame (648), the transducer (102) uses beamforming circuitry to transmit and focus pressure waves from different piezoelectric elements (Fig. 1, 104), such as in one or more specific rows (Fig. 5, 542 ) in the pressure wave. Reflected signals collected by these piezoelectric elements (Fig. 1, 104) are received, delayed, weighted, and summed to form scan lines (650). The focus of attention is then changed to different parts of the frame and the process is repeated until the entire frame (648) is generated including, for example, 100-200 scan lines (650).

Although specific reference is made to a particular transmission technique, many different transmission techniques may be employed, including utilizing a single transmission from multiple channels to achieve multifocality. Furthermore, the operations described in this specification are also applicable to these multi-focus transmission signaling techniques. For example, chirp signaling can be used to achieve simultaneous multi-region focusing and can help achieve better resolution (depending on depth). As a specific example, chirp signaling sends a coded signal during a transmission in which many cycles of a frequency or phase modulated coded signal are sent. The received echoes are then processed using matched filters to compress the received signal. The advantage of this method is that greater energy can be coupled into the target than if only 1 or 2 pulses were sent. Although axial resolution may deteriorate when transmitting multiple signals with chirps, axial resolution is largely restored due to filter matching in the receiver.

One problem with chirp signaling is that it uses many periods of transmit pulses, which increases the power output of transmit pulses of similar amplitude in all signaling situations. However, by electronically adjusting the elevation aperture, the power output can be adjusted to allow the use of various types of signals in B-mode and Doppler imaging, where more pulses are used.

Figure 6B shows the azimuthal axis labeled direction xa. This is the same as the A-A direction in Figure 6A, where line (650) is along the axis shown in Figure 6B and is represented as za or depth in Figure 6B. Figure 6B also indicates the elevation direction ya. The elevation direction may be particularly relevant for 2D imaging. The ultrasound beam as shown is focused in an elevation plane (1201) to focus the beam in a narrow direction and to increase pressure at axially specific points in this plane. The beam is also focused along the azimuthal direction in the azimuthal plane (1202).

As shown in Figure 6B, if the azimuth focus and the elevation focus are relatively located at the same position, the pressure at the target focus increases. The ability to electronically control elevation and azimuth focus allows the operator to target any point in the elevation and axial dimensions, creating a 3D focus with increased pressure at that point. The increase in pressure increases the signal availability of the transducer and also increases the sensitivity. Additionally, if not focused in the elevation direction, the transmitted waveform can hit other objects far away from the elevation plane (1201), and reflected signals from these unwanted targets can create clutter in the received image. Note that Figure 6B shows the sound beam propagating in depth along the axial direction.

Figure 6C shows various types of beam reflecting elements arranged in a row, with a different delay applied to each element in the row. For example, the first beam (4101) has an equal delay for all elements causing the waveform to be delayed equally, resulting in a plane wave called a synchronized beam. Other examples include different delays applied to elements on a row to focus a beam on a point. For a beam focused on a point in the elevation plane, this is called a steered beam or a focused and steered beam. The second beam (4102) shows the focused beam. The third beam (4103) shows the beam with beam steering and the fourth beam (4104) shows the beam with steering and focusing.

Figure 6D shows an example of a transducer with 24 columns and 128 rows, where each row includes 24 elements. Components represented by circles in the row share the same delay and are shaded, while other components have different delays and are not shaded. Each row may have the same relative delay as elements of other rows, or each row may have a different relative delay. The actual delay on any element is the sum of the delays on the azimuth and elevation axes. Control is implemented in an ASIC, which creates pulse drives for the elements with appropriate delays in transmit and receive modes.

In one example, the imaging device includes an electronically implemented transmit elevation focus. For example, electronic focusing is achieved through an ASIC by changing the relative delay of the beams sent by the elements in the row. A digital register in the ASIC is controlled by an external controller, where the required transmit elevation focal depth is sent to the ASIC. The desired azimuth depth of focus is sent by an external controller to the ASIC, where the ASIC sets the relative delays of the elements. Adjust the desired azimuthal depth of focus for curvature in the transducer, ASIC, or plate. The elevation focus can be adjusted electronically to include delay adjustments to compensate for curvature in the transducer. In another example, elevation focus is sending elevation focus. Elevation focus also includes adjusting the receiving elevation focus. Mechanical lenses may be included that provide fixed transmission and elevation focus, and wherein electronic elevation focus allows for further electronic changes in elevation focus. Unit-specific electronic adjustment of the transducer focal length can be used to enhance Doppler imaging sensitivity. Electronic adjustment may include units that adjust for changes in curvature in the transducer.

Figure 7 illustrates the formation of scan lines (650) according to an example of the principles described herein. A cross-sectional view of a transducer (102) is taken along line A-A of Figure 6A and includes the piezoelectric element (104) constituting the transducer (102). In Figure 7, for simplicity, only one piezoelectric element (104) of the transducer (102) is represented by an element symbol. Additionally, note that the piezoelectric element (104) shown in Figure 7 may represent the top piezoelectric element (104) of a row (Figure 5, 542) with other piezoelectric elements (104) extending into the page. Figure 7 also depicts the circuitry that may be found in the controller (324) to form the scan lines (650).

For simplicity, Figure 7 depicts only seven piezoelectric elements (104) and seven corresponding rows (Figure 5, 542). However, as mentioned above, the transducer (102) may include any number of piezoelectric elements (104), such as 128 rows (Fig. 5, 542) of 32 piezoelectric elements (104) per row (Fig. 5, 542). ) placed in it.

To form a scan line (650), a signal (752) is received from a plurality of piezoelectric elements (104), such as from each piezoelectric element (104) in a row (Fig. 5, 542). In some examples, signals for the piezoelectric elements (104) in rows (Fig. 5, 542) may be combined into a composite signal (754) that is passed to the controller (324). Each composite signal (754) is received at a different time due to different transmission lengths, so the controller (324) delays each composite signal (754) so that they are in phase. The controller (324) then combines the adjusted signals to form scan lines (650). Additional details regarding the processing of the received signal (754) by the controller (324) are given in subsequent figures.

As mentioned above, the frame of the image (Fig. 6A, 648) is formed from a number of scan lines (650), typically 128 or more. These scan lines (650) cover the area to be imaged. The time to collect scan lines (650) and combine them into a frame (Fig. 6A, 648) defines the video quality of the object to be imaged in terms of frame rate. For example, taking scanning the heart as an example, and assuming the heart is 20 cm below the surface of the transducer (102), assuming sound travels through the tissue at 1540 m/s, the ultrasound waveform takes approximately 130 microseconds (us) can spread to the heart. The signal then reflects from the heart and takes another 130 microseconds to reach the transducer (102) for a total transmission time of 260 microseconds. Using N receive channels (Fig. 1, 108), a scan line (650) is formed by driving N rows (Fig. 5, 544) of piezoelectric elements (Fig. 1) sent from N transmit channels (Fig. 1, 108), and receives signals from all N rows (Fig. 5, 544) and processes the signals as shown in Fig. 7. In one example, using 128 channels, a scan line is formed by sending from 128 channels, driving 128 rows of piezoelectric elements and receiving and processing signals from all 128 rows. Assuming 128 scan lines (650) per frame (Figure 6A, 648), the maximum frame rate is approximately 30 frames per second (fps).

In some examples, such as for liver and kidneys, 30 fps may be sufficient. However, for imaging moving organs such as the heart, higher frame rates may be desired. Therefore, the imaging device (Fig. 1, 100) can implement parallel beamforming, in which multiple scan lines (650) can be formed simultaneously. Since multiple scanning layers (650) can be formed at one time, the effective frame rate can be increased. For example, if four scan lines (650) can be formed simultaneously, the effective frame rate can rise to 120 fps. Parallel beamforming can be implemented in a field programmable gate array (FPGA) of the imaging device (Fig. 1, 100) or in a graphics processing unit (GPU) (Fig. 3, 326).

In some examples, parallel beamforming is used to initially increase the frame rate even if the frame rate is higher than needed. For example, using parallel beamforming, a frame rate of 120 fps can be achieved. However, if 30 fps is enough, you can enable hardware such as transmit and receive channels for a period of time (say a quarter of the time) to reduce power consumption by 4x or less. Saving time takes into account requirements that are not suitable for complete shutdown, but can be put into a low power state. For example, after collecting a set of four scan lines simultaneously, the transmit (Figure 1, 106), receive channel (Figure 1, 108) and part of the control circuit (Figure 1, 109) can be turned off for a period of time and then turned on again to simultaneously Collect four more scan lines.

Such techniques can reduce power consumption by a larger factor, for example, about 3.3 times less than the starting power consumption value of the cited example. In other words, parallel beamforming is used to increase the frame rate. The next step is to selectively turn off the circuitry involved in creating scan lines to reduce power consumption, and achieve the target frame rate through the turn-off time. This technology reduces power consumption compared to parallel beamforming without circuitry. Such operations do not affect image quality because imaging artifacts can be corrected digitally using power-free operands and can be performed in a display processor that is not located in the probe. Specifically, data from the imaging device (Fig. 1, 100) in the form of scan lines (650) may be transferred to a computing device (Fig. 2, 216) unit using a USB interface, and image processing may be performed externally to the imaging device (Fig. 2, 216) Figure 1, 100), there is less restriction on the temperature rise externally. The amount of scaling depends on the number of parallel beams sent and received. For example, the scaling can be smaller when using two parallel beams and larger when using eight parallel beams.

8 is a method (800) for selectively varying the number of channels of an imaging device (FIG. 1, 100) or the number of elements per channel (FIG. 1, 106, 108) in accordance with an example of principles described herein. flowchart. According to the method (800), an indication is received (block 801) that power consumption or acoustic power output should be adjusted within the imaging device (Fig. 1, 100). This indication can come in many forms. For example, if power consumption is to be reduced because a temperature sensor indicates that the temperature is too high, an indication to reduce power can be sent to the control circuit. In another example, if the acoustic power output is to be changed, the control circuit may receive instructions to change the number of elements sent or the power per element.

In one example, the operator is first guided to obtain medically relevant images by helping to correctly orient the imaging device (Fig. 1, 100) for use. This can be achieved through the use of artificial intelligence technology that utilizes machine learning with algorithms to guide the user to orient the image in the correct direction to obtain the desired view of the organ being imaged (Fig. 2, 214) . After the correct orientation is obtained, the actual imaging process can begin with the relevant resolution. However, during orientation and guidance, high resolution is not required, so the imaging device (Fig. 1, 100) can be set to a lower power and lower resolution mode, thereby saving power throughout the imaging process.

Figure 9 depicts an example receive channel (108) in accordance with the principles described herein. The receiving channel (108) is coupled to the piezoelectric element (Fig. 1, 104) to receive the reflected pressure wave (Fig. 2, 210). Figure 9 also depicts the connection between the piezoelectric element (Figure 1, 104) and the transmission channel (Figure 1, 106). During a transmit operation, the transmit/receive switch is open, isolating the LNA (1056) from the drive signal on Node A. In one example, after the transmit is complete, the transmit channel (Fig. 1, 106) pulse driver is set to a high impedance state to allow the transducer to receive the pressure signal during the receive operation at the node (Fig. 9, A). At this node, the received pressure signal is connected to the LNA via the transmit/receive switch (now on). During the transmit operation, the transmit pulse driver also sends a transmit signal at node A, which is converted by the transducer into an ultrasonic pressure wave and sent to the target to be imaged.

In other words, the receiving channel (108) receives the reflected pressure waveform from the target to be imaged, and the receiving channel (108) converts the pressure into voltage. Specifically, the reflected pressure wave is converted into charge in the transducer and then converted into voltage through the LNA. LNA is a charge amplifier where electric charge is converted into output voltage. In some examples, the LNA has programmable gain, which can be changed in real time and controlled by Cf and Rf, a set of programmable components, as shown in Figure 11. An example of an LNA (1056) with programmable gain is shown in Figure 10.

The LNA (1056) converts the charge in the transducer into a voltage output and also amplifies the received echo signal. The transmit/receive switch connects the LNA (1056) to the transducer in receive operating mode.

The output of the LNA (1056) is then connected to other components to condition the signal. For example, a programmable gain amplifier (PGA) (1058) further adjusts the amplitude of the voltage and provides a way to change the gain based on time, and may be called a time gain amplifier. As the signal travels deeper into the tissue, it is attenuated. Therefore, a larger gain is used for compensation, and this larger gain is achieved by TGC (Time Gain Compensation). The bandpass filter (1060) is used to filter noise from the frequency band signal. An analog-to-digital converter (ADC) (1062) digitizes the analog signal to convert the signal into the digital domain so that it can be further processed digitally. The data from the ADC (1062) is then digitally processed in the demodulation unit (1064) and passed to the FPGA (326) to generate scan lines (Figure 6A, 650), as shown in Figure 7. In some implementations, the demodulation unit (1064) may be implemented elsewhere, such as in an FPGA (326). The demodulation unit (1064) utilizes the two orthogonal components (I and Q) to frequency-shift the carrier signal to the fundamental frequency for further digital processing. In some examples, the ADC (1062) may implement a sequential asymptotic register (SAR) architecture to reduce the latency of the ADC (1062). That is, as the ADC (1062) is turned off and turned on repeatedly, it requires little or no latency and therefore does not delay signal processing after turning on.

Figure 10 depicts a low-noise amplifier (LNA) (1056) of the receive channel (Figure 1, 108) according to an example of principles described herein. Capacitor banks C _f1 -C _fn are electronically selected by turning on switches M ₁ -M _n , and capacitors C _f1 -C _fn are connected across the operational amplifier (1166). R _f1 -R _fN is a set of resistors, which can also be selected electronically by turning on switches S ₁ -S _N. Signal gain is the ratio of the transducer capacitance C _p divided by the feedback capacitance C _f , in which case the appropriate switches are turned on to connect the C _f and R _f values from the capacitor bank as needed. The bias voltage (VBIAS) is used to provide a bias voltage so that the polarity of the field across the transducer does not change as the signal swings in the positive or negative direction on the opposite electrode of the transducer.

Figure 10 also depicts the bias current input (IBIAS). IBIAS can be generated by the circuit shown in Figure 11. IBIAS is used to change the transduction of the LNA (1056), where higher current levels reduce noise levels. Additionally, a digital input indicating power outage is used to shut down the LNA (1056). To achieve fast power-up, IBIAS needs to be set up quickly using the example implementation shown in Figure 11.

Figure 11 shows a circuit diagram of an example fast power-up bias circuit (1268) in accordance with the principles described herein. As mentioned above, when the receive channel (Fig. 1, 108) is opened and closed multiple times during operation, the assembly can be opened and closed quickly to ensure proper heat dissipation and proper operation of the imaging device (Fig. 1, 100). In this example, the IOUT terminal is coupled to the LNA's IBIAS (Figure 10, 1056) to ensure fast power-up of the LNA (Figure 10, 1056). To effectively implement the imaging device (Fig. 1, 100), components in the signal path such as the LNA (Fig. 10, 1056) and ADC (Fig. 10, 1064) in each receive channel (Fig. 1, 108) can be Powers down in about a few hundred nanoseconds and powers up in about 1 us. The fast power-up bias circuit (1268) shown in Figure 11 is an example of providing such fast power-up and shutdown. The bias circuit (1268) shown in Figure 11 exhibits fast turn-on and turn-off times. If the Power Down signal is high, the Power Up boot is low, closing switches S1-S3 so that they do not conduct current and reducing the value of IOUT, effectively turning them off. When Power Down goes low (i.e., it is desired to power up the LNA (1056)), or both inputs of the NOR gate are low, this generates a high logic signal during the Power Up boot sequence. This turns on switches S1-S3 and quickly restores current to IOUT. IOUT provides a current output whose value will be copied into other circuits, such as an LNA (Figure 10, 1056), to power these circuits. The value of IOUT is close to zero during shutdown and has a higher value during power-up, typically tens or hundreds of µA.

Figures 12-16 illustrate the fabrication of an example piezoelectric element (Figure 1, 104) in accordance with the principles described herein. Figure 12 shows a top view of membrane (1374) disposed on substrate layers (1370) and (1372). Figure 13 shows a cross-sectional view of membrane (1374) and substrate (1372) taken along line B-B in Figure 12.

Figure 14 shows a top view of a bottom electrode (1578) disposed on a substrate layer (1370) and above a membrane (1374) in accordance with an example of principles described herein. Figure 15 shows a top view of a piezoelectric layer (1680) disposed on a bottom electrode (Figure 14, 1578) according to an example of the principles described herein. In some examples, piezoelectric layer (1680) can have a similar protruding area as bottom electrode (1578) such that piezoelectric layer (1680) can cover an entire portion of bottom electrode (1578).

Figure 16 shows a top view of an example piezoelectric element in accordance with the principles described herein. As shown, a top electrode (1782) is disposed on the piezoelectric layer (1680) and disposed on the membrane (Fig. 13, 1374). In some examples, top electrode conductor (1783) can be disposed on and electrically coupled to top electrode (1782), while bottom electrode conductors (1784-1) and (1784-2) can be transparent to one or A plurality of vias (1790-1, 1790-2) reach the bottom electrode (1578). In this example, the top electrode (1782), the piezoelectric layer (1680), and the bottom electrode (1578) form a two-terminal piezoelectric element, and when a voltage is applied across the top and bottom electrodes (1782, 1578), the membrane ( 1374) vibration. When the membrane (1374) deforms due to pressure waves (Fig. 2, 210) during receive mode/processing, charges can be generated on the top and bottom electrodes (1782, 1578).

The substrate (1372) may be thinned to prevent crosstalk between adjacent piezoelectric elements, where thinner materials do not support the propagation of ultrasound waves in the substrate (1372) between activated elements or sub-elements. Figures 17A-17B illustrate component construction to achieve isolation and reduce crosstalk between adjacent components. Substrate (1372) may correspond to transceiver substrate (540) in Figure 5. As shown, a film (1374) may be formed on a substrate (1372), the film (1374) having a cavity (1376) formed by removing a portion of the substrate (1372), thereby forming the film (1374), the film (1374) The direction of vibration may be vertical relative to the vertical direction of the substrate (1372). The cavity (1376) may be formed through wafer processing techniques such as etching, such as deep reactive ion etching (DRIE). Substrate (1372) may be formed from the same material as membrane (1374). In another example, substrate (1372) may be formed of a different material than membrane (1374). The cavity (1376) (see Figure 13) may be formed after the other components of the piezoelectric element (Figure 1, 104) are formed. Although FIG. 13 and other figures herein depict membrane (1374) as having a circular projected area, membrane (1374) may have other suitable geometries.

Specifically, Figure 17A shows a membrane (1374) formed on a substrate (1372) with a cavity (1376) located beneath the membrane (1374). The membrane (1374) is surrounded on all sides by the substrate (1372) material. Figure 17B shows four membranes (1374) separated by a base plate (1372). Piezoelectric elements (Figure 1, 104) may need to be isolated from each other to minimize crosstalk. Crosstalk is the effect of one piezoelectric element (104 in Figure 1) on another piezoelectric element (104 in Figure 1) through acoustic or mechanical or electrical coupling. Such coupling is generally undesirable as it makes each membrane (1374) less independent. In some examples, piezoelectric elements (Fig. 1, 104) are separated by grooves or grooves (1373) cut in the substrate (1372), and the grooves or grooves (1373) attenuate propagation toward their neighbors. signal, as shown in Figure 17B. The trench (1373) can be air filled or vacuum. This presents impedance discontinuities between adjacent regions and attenuates energy flowing from a piezoelectric element (Fig. 1, 104) to its neighboring piezoelectric element (Fig. 1, 104). It will be appreciated that even if some figures do not show this trench, they are incorporated by reference from this description.

Figure 17C shows a transducer element attached to an electronic device using two attachment points labeled X and O. Transducer (1420) includes a substrate (1411), a membrane (1406), a piezoelectric material (1409), another material or coating attached to the transducer surface (1403), and electrodes (1407) and (1410 ). The first electrode (1407) is connected to the pillar (1402) through a wire (1408). Piezoelectric material (1409) is provided on the electrode (1407). The second electrode (1410) is disposed on top of the piezoelectric material (1409) and connected to the pillar (1414) through a wire (1405). The ASIC (1417) is shown below the transducer (1420) and is connected to the transducer (1420) through two struts (1401) and (1415) for each element of the transducer (1420). Legs (1401) and (1402) are connected to the common terminal of an element called the X node, which is connected to the DC bias voltage. The sending or receiving terminal of an element is called an O node. Connect struts (1414) and (1415) to connect transducer (1420) to the ASIC O node. Pillars (1401) and (1402) are tied together to integrate elements of the transducer (1420) into associated electronic components in the ASIC (1417).

Similarly, struts (1414) and (1415) are tied together to integrate elements of the transducer (1420) into associated electronic components in the ASIC (1417). The space between the transducer (1420) and the ASIC (1417) may be air filled or vacuum. The surface of transducer (1420) facing ASIC (1417) may have a coating (1403) to absorb or attenuate acoustic energy propagating from transducer (1420) in the direction of ASIC (1417). Additionally, as shown, an acoustic absorbing layer (1404) may be attached below the ASIC (1417) to absorb acoustic energy propagated from the transducer (1420) through the ASIC (1417). The area covering the substrate (1411) and the membrane (1406) (i.e., in the cavity area and the entire surface of the substrate 1411) is filled with an impedance matching material, forming the interface between the transducer (1420) and the target to be imaged. In some cases, the material beneath the membrane (1406) is made to have a different acoustic impedance compared to the material in the remainder of the substrate (1411). This mismatch in impedance can also disrupt possible acoustic coupling between adjacent elements or sub-elements as acoustic energy passes through the impedance matching layer.

In some examples, a piezoelectric element (Fig. 1, 104) has a suspended membrane associated with it, and when exposed to stimulation at this frequency, this membrane vibrates at the center frequency and several other frequencies, thus behaving like a resonance device. The selectivity associated with these resonators is called the Q-factor. For ultrasound imaging devices (Fig. 1, 102), Q can usually be designed to be low (close to 1) and achieved by combining the design of the pixels and the load applied to the pixels in actual use. Loading can be provided by applying a layer of RTV or other material to the surface of the piezoelectric element (Fig. 1, 104), where the loading can also facilitate communication between the transducer surface that sends and receives pressure waves and the body part being imaged. Tight impedance matching. Low Q and well-matched center frequencies can allow line elements to behave essentially like line imaging elements with essentially one center frequency. The load may also include a matching layer beneath the transducer where the transmitted waveform is absorbed by the acoustic absorber.

Figure 18 shows a schematic diagram of an example piezoelectric element (1800) in accordance with the principles described herein. The piezoelectric layer (1880) is disposed between the first electrode (1882) and the second electrode (1878). The first electrode (1882) can be connected to ground or DC bias via a first conductor (1886), and the second electrode (1878) can be connected to a circuit (not shown in Figure 18) via a second conductor (1890).

In traditional piezoelectric elements, the piezoelectric layer is thick, approaching 100 μm, and an AC voltage of +100 to -100V across the piezoelectric layer is typically required to generate ultrasonic pressure waves with sufficient intensity to enable medical imaging. The frequency of the AC drive signal is typically around the resonant frequency of the piezoelectric structure and is typically above 1 MHz for medical imaging applications. In conventional systems, the power consumed in driving the piezoelectric element is proportional to f*C*V ² , where C is the capacitance of the piezoelectric element, V is the maximum voltage on the piezoelectric layer, and f is the driving frequency. Typically, when transmitting a pressure wave, multiple piezoelectric wires are driven together with slightly different phase delays to focus the pressure wave or control the propagation direction of the pressure wave.

In the piezoelectric element (1800) of this specification, the piezoelectric layer (1880) can be thinner, for example, 1-5 μm thick. This substantial reduction in thickness enables the use of lower voltage drive signals for the piezoelectric element (1800), where the voltage is reduced approximately by the thickness reduction of the piezoelectric layer (1880) to maintain similar electric field strengths. For example, the peak-to-peak potential between the two electrodes (1882) and (1878) may range from approximately 1.8V to 40V. The capacitance of the piezoelectric element (1800) may increase due to the reduction in thickness of the piezoelectric layer (1880) of similar piezoelectric material. For example, when the driving voltage is reduced by a factor of 10 and the thickness of the piezoelectric layer (1880) is also reduced by a factor of 10, the capacitance increases by a factor of 10 and the power consumption is reduced by a factor of 10. The reduction in power consumption also reduces heat generation and temperature rise in the piezoelectric element (1800). Therefore, using a lower driving voltage and a thinner piezoelectric layer reduces power consumption compared to conventional piezoelectric elements, and this also reduces the temperature of the piezoelectric element (1800) during operation.

Figure 19A is a schematic diagram of a piezoelectric element (1900) according to another example of the principles described herein. Figure 19B shows a symbolic representation of the piezoelectric element (1900) in Figure 19A. As shown, piezoelectric element (1900) is similar to piezoelectric element (1800) except that piezoelectric element (1900) has more than two electrodes. More specifically, the piezoelectric element (1900) includes: a top electrode (1982), a first bottom electrode (1978-1); a second bottom electrode (1978-2); a piezoelectric layer (1980) disposed on the top and Between the bottom electrodes; three conductors (1984-1), (1984-2), (1984-3) electrically coupled to the top and bottom electrodes (1982), (1978-1), (1978-2) respectively. In the following, the terms top and bottom only refer to the two opposite sides of the piezoelectric layer, ie the top electrode does not necessarily have to be arranged above the bottom electrode.

The piezoelectric element (1900) shown in Figure 19A is particularly helpful in increasing the sensitivity of transmit and receive operations. For example, when piezoelectric materials are manufactured, the dipoles in the piezoelectric material are misaligned, and to obtain optimal piezoelectric performance, a polarization process is implemented in which the piezoelectric film is heated at high temperatures (e.g., 175°C) A strong electric field is applied. This determines the direction of the electric field for subsequent operations. However, the sensitivity of the piezoelectric elements used for basic transmit and receive operations can be enhanced if they are polarized in orthogonal directions. For receiving pressure waves, the piezoelectric element develops more charge signals during the receiving operation, resulting in more pressure for a given transmit voltage drive.

The piezoelectric element (1900) in Figure 19A contains 3 wires, of which the first wire (1984-1) can be grounded during the polarization operation and the second wire (1984-2) can be at a high voltage (e.g. positive 15V ), the third wire (1984-3) can be at -15V. Therefore, during this polarization operation, orthogonal electric fields are established in the sub-elements of the piezoelectric element (1900). In actual use, the second wire (1984-2) and the third wire (1984-3) can be tied to the DC bias voltage and act as virtual ground, while the first wire (1984-1) is used to send and receive operation.

Although a single piezoelectric wafer piezoelectric element is shown in FIG. 19A for illustrative purposes only, in embodiments, a multilayer piezoelectric element composed of a plurality of piezoelectric layers and electrodes may be utilized. In embodiments, the piezoelectric layer (1980) may include at least one of PZT, PZT-N, PMN-Pt, AlN, Sc-AlN, ZnO, PVDF, and LiNiO3.

Figure 19B shows a symbolic representation of the piezoelectric element of Figure 19A according to an example of the principles described herein.

Figure 19C shows a schematic cross-sectional view of an example piezoelectric element (1900) in accordance with principles described herein. The piezoelectric element (1900) may be disposed on the substrate layer (1970). The substrate layer (1972) together with the substrate layer (1970) constitute the substrate. A cavity (1976) may be formed in the substrate layer (1972) to define a membrane (1374). Membrane (1374) is the portion of substrate layer (1970) that overlaps cavity (1976) and is shaped like cavity (1976). Substrate layers (1972) and (1970) may be made of the same material, and may also be formed of a single continuous material.

Piezoelectric element (1900) may include a piezoelectric layer (1980) and a first electrode (1982) electrically coupled to a top electrode conductor (1984-1). The top electrode conductor (1984-1) can be formed by depositing TiO2 and metal layers on the membrane (1374).

A first bottom electrode (1978-1) may be grown over the piezoelectric layer (1980) and electrically connected to the first bottom conductor (1984-2). A second bottom electrode (1978-2) may also be grown over the piezoelectric layer (1980) and disposed adjacent to the second bottom conductor (1984-3) but electrically isolated from the first bottom conductor (1984-2). The second bottom electrode (1978-2) and the second bottom conductor (1984-3) may be formed by depositing a metal layer on the piezoelectric layer (1980) and patterning the metal layer. In some examples, the projected area of the electrode (1984) may have any suitable shape, such as square, rectangular, circular, oval, etc.

The first electrode (1982) may be electrically connected to the conductor (1984-1) using metal, vias, and interlayer dielectrics. In some examples, first electrode (1982) may be in direct contact with piezoelectric layer (1980). A second bottom conductor (1978-2) may be deposited or grown on the other side of the piezoelectric layer (1980) relative to the first electrode (1982).

Figure 19D shows a schematic diagram of a piezoelectric element (1992) according to another example of the principles described herein. As shown in the figure, the piezoelectric element (1992) consists of two sub-piezoelectric elements (also called sub-elements) (1996-1) and (1996-2). Sub-elements (1996-1) and (1996-2) are contiguous, thus improving space utilization.

Each sub-element (1996-1) and (1996-2) may include a double-ended device. For example, the subelement shown (1996-1) includes a bottom electrode (1982-1), a top electrode (1978-1), a membrane (1374-1), and a piezoelectric layer (1980-1). The designation top or bottom does not physically mean one is above the other, but is used to indicate that the electrodes are in different vertical positions, and top and bottom are used interchangeably. Another subelement (1996-2) has a bottom electrode (1982-2), a top electrode (1978-2) and a piezoelectric layer (1980-2) (see ibid.). Each sub-element (1996-1) and (1996-2) may be provided on a separate membrane (1374-1) and (1374-2). Membranes (1374-1) and (1374-2) are separated by a solid region (1399) made of a solid substance such as silicon dioxide. When subcomponents (1996-1) and (1996-2) are active, they can affect the behavior of each other or adjacent subcomponents. This can occur by transferring energy from one sub-element to another or from one element to another. This transfer may occur, for example, by ultrasound propagating through the solid region (1399) from the sub-element (1996-1) to the sub-element (1996-2) and vice versa. It is beneficial to minimize this interaction to minimize crosstalk.

An example of crosstalk reduction is through trenches such as the trench shown in Figure 19E (1997). The trench (1997) can be air-filled or vacuum-filled (e.g., by incorporating a cover over the trench). Trenching can be used for subelements (1996-1) and (1996-2) in Figure 19D to reflect the crosstalk causing wavefront return. Other crosstalk minimization techniques can also be implemented. For example, an impedance matching layer (not shown) may be applied over the transducer surface and solid area (1399) to have a different acoustic impedance compared to the material on the membrane area 1374. This disrupts the propagation of sound waves from one sub-element to another through the acoustic medium in the impedance matching layer.

Ultrasonic waveforms propagating in solids may be reflected back from the trench area, preventing or reducing forward propagation of the waveform in the trench area. It should be apparent to one of ordinary skill in the art that conductors (e.g. 1984-1, 1984-2 and 1984-3) can be bonded to corresponding electrodes (1978-1) and (1978-2) using metal via interlayer dielectrics quality (ILD), etc., in a similar manner to the piezoelectric element shown in Figure 12-16. For simplicity, not all conductor connections are shown.

Sub-elements (1996-1) and (1996-2) can be further used for CW Doppler, where the transmitting element transmits continuously and the other element receives continuously. Continuous transmit and receive operations help the imaging technique not suffer from the aliasing problems that accompany sampled Doppler methods such as PW or color Doppler. Aliasing limits the maximum flow rate that can be measured reliably to half the pulse repetition frequency. Different areas of the transducer are typically used for continuous transmission and continuous reception, so the elements are widely separated to minimize crosstalk.

In some examples, sub-elements (1996-1) and (1996-2) as shown in Figure 19D can have different center frequencies and, when operated together as a single composite element, exhibit a wider bandwidth. Subcomponents (1996-1) and (1996-2) still operate as double-ended devices when the top and bottom terminals of subcomponents (1996-1) and (1996-2) are joined together. This wide bandwidth performance can also be achieved using the structure shown in Figure 19C. The sensitivity in this structure can be further improved using dual polarization techniques.

Figure 19E shows a representative example of an imaging device in which one sub-element (2997-1) is configured to be continuously in a transmit mode and another sub-element (2997-2) is configured to be continuously in a receive mode. The imaging device includes a first top electrode (1982-1) and a second top electrode (1982-2), a first bottom electrode (1978-1) and a second bottom electrode (1978-2); a piezoelectric layer (1980-1 ), arranged between the top electrode (1982-1) and the bottom electrode (1978-1); the piezoelectric layer (1980-2), arranged between the top electrode (1982-2) and the bottom electrode (1978-2) ; and two conductors (1984-1) and (1984-2) electrically coupled to respective top and bottom electrodes (1982-1), (1978-1) and (1982-2), (1978-2). In the following, the terms top and bottom refer only to the two opposite sides of the piezoelectric layer.

A trench (1998) is provided between the membrane (1374-1) of the subelement (2997-1) and the membrane (1374-2) of the subelement (2997-2) to minimize the subelement (2997-1) and ( 2997-2). In one example, CW Doppler imaging may be performed using one of the sub-elements (2997-1) for transmitting and the other sub-element (2997-2) for receiving. This allows efficient use of the aperture size (Fig. 21, 3412) where transmit and receive elements can be adjacent. When performing CW Doppler imaging by continuously programming one element to be in transmit mode of operation and another element in a different part of the imager to be continuously in receive mode, the noise from these two Crosstalk from elements is relatively small because they are spatially separated by a large distance relative to the size of the transducer. For PW operation, the same subelement can be used for transmitting and then switched to receive mode.

Figure 19F shows an example of reducing crosstalk between adjacent elements. In this example, membranes 2905-1, 2905-2 are electrically simulated by electrodes (Fig. 19E, 1982-1, 1982-2 and 1978-1, 1978-2), which results in ultrasonic waveforms along regions 2902-1 and 2902 -2 direction transmission. Laterally propagating wave fronts 2901-1, -2 are reflected and attenuated by grooves 2998-1, -2, -3. Regions 2903-1, -2, -3 represent materials designed to match the impedance of the transducer to tissue. Areas 2903-1, -2, -3 have different impedances than areas 2902-1, -2. Therefore, the side-propagating wavefronts 2901-1, -2 are reflected by the mismatch and attenuated, which reduces crosstalk. For example, the materials may be mismatched by applying an acoustic lens layer to the bottom surface of one or more regions 2903-1, -2, -3 and 2902-1, -2. In some embodiments, the material in one or more regions 2903-1, -2, -3 and regions 2902-1, -2 remains the same.

Figure 19G shows an example of reducing crosstalk between adjacent elements. In this example, multiple trenches 3998-1, -2, -3 and 3999-1, -2, -3 are utilized to isolate coupling between adjacent elements or sub-elements, thereby providing crosstalk isolation. The trenches 3998-1, -2, -3 begin on opposite sides of the substrate 3002 from the trenches 3999-1, -2, -3. The first trench (3998-1) starts from the top surface, while the second trench (3999-1) starts from the bottom surface. Likewise, other grooves (3998-2, 3999-3) start from the top surface, and still more grooves (3999-2, 3993-3) start from the bottom surface. The connections (3000-1, 3000-2, 3000-3) establish electrical connections between the controller (3200), such as an ASIC, and the structure (3300) containing the diaphragm, which may be a microelectromechanical systems (MEMS) structure. The double groove structure isolates the vibration energy transmitted from the controller (3200) through the links (3000-1, 3000-2, 3000-3) and then transferred to the adjacent components, as shown in (3001), indicating that for use with Vibration coupling of the components of the cavity (3901-1, 3901-3) is reduced. Typically, two trenches provide higher isolation than one trench. Such a topology may be referred to as forward transmit, where the cavities (3901-1, 3901-3) face the ASIC controller (3200). In some examples, linkage (3000-2) supports membrane (3905-2). Please note that the figures are not to scale and are used only to illustrate the principle of operation.

In one example, an ASIC is attached to a substrate and electrically coupled to enable anatomical and Doppler flow imaging, with each piezoelectric element exhibiting a plurality of vibration modes. Imaging can be performed by the transducer at low frequencies, such as for abdominal or cardiac imaging, or at higher frequencies, for musculoskeletal (MSK) or vascular imaging.

In one example, the membrane is attached to the ASIC in a backward orientation, with the cavity facing the imaging target. In another example, the membrane is coupled to the ASIC in the forward transmit direction, with the cavity facing the ASIC and the membrane transmitting and receiving from the front.

In another example, an imaging device includes a MEMS-based element with a wide bandwidth. The imaging performed by the transducer can be used for low-frequency imaging, such as abdominal or cardiac imaging, or for high-frequency imaging, such as musculoskeletal (MSK) or vascular imaging.

In another example, the imaging device also includes MEMS-based elements with wide bandwidth. Imaging can be performed by the transducer for abdominal or cardiac imaging or high frequency imaging (MSK) or low frequency imaging for vascular imaging.

Figure 19H shows an example of reducing crosstalk between adjacent elements. Compared with Figure 19G, the orientation of the vibrating membrane is flipped. The orientation of Figure 19G is called forward transmission, and the orientation of Figure 19H is called backward transmission. In this example, the cavities (3901-1, 3901-2) face away from the ASIC controller (3200) and face the target to be imaged. In this example, since the metallization and connections on the MEMS structure (3300) are a few microns apart from each other (as well as metal vias and other connections that do not require TSVs), it is possible to operate without TSVs (through silicon vias). In this case, links (3000-1, 3000-2 and 3000-3) are made to the ASIC controller (3200). TSVs are difficult to manufacture and add cost and complexity to the manufacturing process. In the back-send topology shown in Figure 19H, trenches (3999-1, 3999-2, and 3999-3) start from the bottom surface of MEMS structure 93300, while other trenches (3998-1, 3998-2, and 3998-3) starting from the top surface to the links (3000-1, 3000-2 and 3000-3). As mentioned above, the use of two grooves (3998-2 and 3999-2) and similar structures on the other side of the link (3000-2) facilitates the separation between the membranes (3905-1 and 3905-2). Additional isolation is provided between, as indicated by coupler (3001). The coupler (3001) is shown from the side facing the target to be imaged. However, as shown in Figure 19G, coupling from the controller (3200) side of the ASIC also applies to Figure 19H, as the dual trenches help isolate coupling between adjacent membranes from the front or back side of the MEMS structure (3300) .

Although two trenches are shown (3998-2 and 3999-2), a single trench may be used. For example, a trench associated with the top surface, such as trench (3998-2), may be used alone, or a trench associated with the bottom surface, such as trench (3999-2), may be used. A single trench from the top or from the bottom may also be sufficient to provide isolation for other applications described herein.

Figure 19I shows a cross-sectional view of an example piezoelectric element (1923) in accordance with principles described herein. As shown, a piezoelectric element (1923) can utilize a lateral mode of operation and includes a substrate (1925-1, -2), a membrane (1927) with one end secured to the substrate, a bottom electrode (1931) electrically coupled to a conductor (1931) 1929), a piezoelectric layer (1933), and a top electrode (1935) electrically coupled to a conductor (1937). The membrane (1927) can be fixed at one end to the substrate (1925-1, 1925-2) so as to vibrate in a transverse mode. The membrane (1927) can be supported on both sides by the base plates (1925-1, 1925-2). It is noted that all previous examples of piezoelectric elements can be operated in a transverse operating mode and all sides of the membrane (1927) can be supported on the substrate. The lateral operating mode and its principles apply to all examples discussed in this article.

Note that the piezoelectric element (1923) can have any suitable number of top electrodes. Additionally, it should be noted that more than one piezoelectric element can be mounted on the membrane (1927). Note also that the substrate (1925-1, 1925-2) and the film (1927) can be formed in one piece, and the film (1927) can be formed by etching the substrate (1925-1, 1925-2).

Color Doppler flow mapping uses multi-gate sampling of multiple scan lines using waveform pulse trains of several cycles at the carrier frequency to which the transducer responds. Figure 20A shows several pulses 2102-1, 2102-2, 2102-3 and 2102-4 that make up the whole. Each pulse contains at least one or more cycles, and its carrier frequency is usually between 2-10 MHz.

Figure 20B shows the colored window (2110) inside the frame (2108) of the transducer 2100. Several scan lines are shown (2104), each scan line having multiple strobe pulses. Successive sampling of the signal along the scan line (2104) is timed according to the depth of the sampling location. Each returning echo is referenced to its range gate, which identifies the echo by its spatial location of origin and is processed electronically by an appropriate delay. After all echoes from the first pulse are received, a second pulse is sent in phase with the first pulse on the same scan line (2104). Proper timing of the pulse repetition frequency is important because one pulse must return before the other pulse ends, otherwise range ambiguity will occur. Once a scan line has been sampled, the next scan line is completed in the same manner, and the color flow map is completed by sweeping multiple scan lines across the color window used.

To determine the average Doppler shift, each echo from each pulse from a specific range gate is compared to its previously sampled pulse from the same range gate. Use the autocorrelation technique to obtain the average Doppler phase shift. Echo samples can be appropriately delayed relative to previous similar echoes from the same line, allowing the results to be multiplied and integrated to achieve automatic correlation. The autocorrelator measures the phase difference from two consecutive echoes. Static parts of the target (i.e. not related to flow) do not show phase differences, but the phases of moving items (such as blood) will.

Doppler imaging is sensitive to noise. Gain control can be used for signal amplification. Separate controllers can be designed for pulse echo imaging and color Doppler functions. The greater the color Doppler gain, the more sensitive the imaging. However, increasing gain also increases noise from the physical components in the imager. The key component of this noise comes from the receiver's LNA, so you may want to achieve a very low noise floor for these LNAs. Since low background noise causes high power consumption and thermal heating in the transducer, the LNA in the imager can be designed to be active only during the enabled color flow window, leaving other LNAs in the imager in a low power state. In addition, the active LNA can be electronically adjusted to optimize performance based on required power and noise levels.

High-pass filters can be used to eliminate high-amplitude, low-frequency Doppler-shifted signals produced by motion of blood vessel walls, moving tissue, and heart motion. These signals have a higher power content that may disrupt lower level signals such as blood flow. High-pass filters block low-frequency information from these spurious moving structures. However, it can also block low-velocity blood flow signals that are present in some target types but not others. Therefore, any hardware-based filter also needs to be programmed for the cutoff frequency. Then, increase the minimum filtration level through the wall filter implemented in the software. The wall filter's high-pass function has an adjustable threshold level and a sophisticated ability to differentiate between low-velocity blood flow and wall motion. They also respond to different applications, frequencies used and pulse repetition rates. In an exemplary embodiment, programmable high-pass functionality is built into the imaging head surrounding the LNA. This allows the implementation of a high-pass filter function with a high-pass filter function in a wall filter later in the signal chain.

The Doppler shift is sensitive to the flow axis and the resonance angle of the ultrasound beam (see equation above). The signal may also disappear completely if the angle is zero (see equation above). The angle can be improved by physically moving the probe where possible. However, in exemplary embodiments, the scan lines may also be electronically controlled in a 2D or 3D manner when using a 2D matrix of elements, where each element has independent control of Tx and Rx functions, including time delays. Therefore, the desired angle can be obtained electronically by steering the beam to the desired position. In such an arrangement, each element can be electronically selected and placed in Tx or Rx mode independently of adjacent or adjacent elements, and appropriate timing delays can be applied to those in Tx or Rx mode. element.

As mentioned above, Doppler imaging is sensitive to noise and signal-to-noise ratio. Therefore, it is desirable to increase the signal in the examples described herein. Traditionally, 2D imagers use mechanical lenses with curvature in the elevation direction to focus energy in the elevation plane. This results in increased pressure on the elevation focus and increases sensitivity. However, this configuration produces a fixed focal length that cannot be adjusted. In the examples disclosed herein, electronic focusing is implemented as 2D imaging using an array of 2D elements. In addition, the mechanical lens is retained. Using the electronic capabilities of the 2D array it is possible to electronically change the focus and also focus in three dimensions. As mentioned above, the steering capabilities shown in Figure 6C allow the beam to be manipulated to further improve Doppler sensitivity. Electronic focusing in the elevation plane can also be achieved by applying different relative delays to the elements in the row. For example, in Figure 5, elements 104 are arranged in rows and columns, with reference numeral 542 indicating a row. As shown in Figure 6C, delays relative to each other in the sent drive signals to each of these elements create a focusing pattern or beam steering.

Additionally, the transducer elements may be in a curved plane as shown in Figure 4. This curvature may be created intentionally or unintentionally due to stress on the board on which the transducer and ASIC are mounted, or due to stress on the integration of the transducer and ASIC. This may vary from unit to unit. The predetermined focus, which is the same for all devices, will produce errors in the actual focus due to curvature. However, the curvature of each unit can be measured on the production line. This information is then used to apply relative delays to components that compensate for these delays. The external controller sends the required latency information to the ASIC. The ASIC applies the compensated delay to each element and restores the high signal pressure output that was reduced due to uncompensated curvature in the transducer elements.

In one example, the transducer can be a broadband multi-modal device, where the membrane can vibrate at multiple different frequencies spread over a broadband simultaneously, thereby forming a broadband transducer. This operation is valid in both send mode and receive mode. This enables B-mode anatomy and Doppler-based imaging of flow over a wide bandwidth and allows the use of the same imager for many applications that would normally require a separate imager to cover a limited bandwidth range.

Although piezoelectric elements can exhibit multiple vibration modes, in some examples only one vibration mode is triggered when the bandwidth limit of the input stimulus is smaller than the frequency of adjacent modes. Furthermore, the frequency generated by the first vibration mode may be designed to overlap the frequency generated by the second vibration mode. Furthermore, in some examples, multiple vibration modes occur simultaneously when driven by a broadband frequency input including a center frequency.

In summary, an imaging device is described that utilizes an array of PMUT-based transducers coupled to control electronics on a per-element basis and housed in a portable housing. The imaging device allows for real-time system configurability and adaptability to proactively control power consumption, temperature, and acoustic power in the imaging device. Beam steering in 3D space can also be achieved. Elements can be programmed to be in receive or transmit mode. Electronics capable of enabling B-mode anatomical imaging and Doppler-mode flow imaging over a wide bandwidth typically rely on multiple transducers using conventional bulk piezoelectric imaging.

Another example imaging device includes at least one piezoelectric transducer. The transducer imaging device includes at least one piezoelectric element. A two-dimensional (2D) array of piezoelectric elements is arranged in rows and columns on a piezoelectric transducer. Each piezoelectric element includes at least two terminals. Each piezoelectric element can be physically isolated from each adjacent piezoelectric element to reduce crosstalk. The first row of piezoelectric elements includes each piezoelectric element, each piezoelectric element having a first top electrode programmed to connect to a corresponding receive amplifier. The second row of piezoelectric elements includes each respective piezoelectric element programmed to be coupled to a respective transmit driver. Each of the individual piezoelectric elements in the first row can be electronically programmed as if linked together to form a row. Each of the individual piezoelectric elements in the second group may be electronically programmed as if linked together to form a row. Additionally, any number of adjacent rows can be programmed to operate in receive mode, while a different number of rows located elsewhere can be programmed to operate in transmit mode. In some examples, multiple vibration modes can be exhibited in each piezoelectric element. A single receive amplifier may be used, with at least one piezoelectric element in the first row coupled to the receive amplifier. Likewise, there can be a single transmit driver, with at least one of the piezoelectric elements in the second row connected to the transmit driver. The electronically programmed connection of piezoelectric elements enables the connection of any number of piezoelectric elements in a row.

In some examples, at least one sub-aperture can include at least one row of piezoelectric elements, and each piezoelectric element can include two sub-elements. Each sub-element can be selected to operate with programmable transmit and receive functionality such that a first sub-element can transmit simultaneously while receiving a second sub-element, and each sub-element can be switched between transmit mode and receive mode. At least one piezoelectric element may include two sub-elements and two terminals, each sub-element having a different center frequency and bandwidth, such that when they are used in parallel, the piezoelectric element itself exhibits a wider bandwidth than either sub-element. bandwidth. In one example, at least one piezoelectric element is used for B-mode and Doppler flow measurements. In one example, each piezoelectric element includes two sub-elements for CW Doppler imaging, and at least a first piezoelectric element is placed in transmit mode while the second piezoelectric element is simultaneously placed in receive mode.

The connections of the piezoelectric elements in at least one of the columns and rows are electronically programmable such that any number of piezoelectric elements in the columns and rows can be connected.

The first piezoelectric element of the array can be continuously in the transmit mode while the second piezoelectric element of the array is continuously in the receive mode to achieve continuous wave (CW) Doppler imaging. A set of lines can be transmitted continuously, while at the same time a set of lines can be programmed to be in receive mode, which also makes CW Doppler imaging possible. Regions can be separated to minimize crosstalk between the transmit and receive portions of the transducer array. The acoustic power output is adjusted by electronically adjusting the height of the rows, etc. (specifically the number of piezoelectric elements making up the rows). Therefore, the acoustic output power is adjusted by electronically adjusting the number of elements involved in transmission. The power source can be the same for Doppler-based flow imaging and anatomical imaging. However, Doppler imaging involves more pulses than B-mode imaging. Therefore, more acoustic power output is produced under similar conditions during flow imaging compared to B-mode, which may exceed regulatory limits. Acoustic power output for flow imaging can be optimized by electronically adjusting the number of components that provide the acoustic power. Additionally, the pulse amplitude generated on each element can be electronically selected when using the same power supply for all imaging modes. This allows tuning of the acoustic power as needed, as well as low-cost, small-footprint power management circuitry to power flow and anatomical imaging. This is helpful for low-cost portable imagers. In one example, the same amount of power is used for Doppler mode and B-mode by electronically modulating the acoustic power transmitted from at least a portion of the array of piezoelectric elements. In one example, the power from each piezoelectric element is regulated by sending the appropriate level of the pulser output using multiple levels. In an example, B-mode and Doppler modes maintain specific power levels, such as acoustic power levels and specific mechanical specifications while using the same power source for the imaging mode.

In each example, each piezoelectric element is used as if connected to a transmit and receive channel to perform the operations described in this specification. Channels can be in a constant state in which they remain transmit, receive, or both transmit and receive channels. Alternatively, there may be changing states where the channel changes between one of the state types of send, receive, and both send and receive.

Additionally, each piezoelectric element within a separate, independent array may exhibit one or more vibration modes. In one example, the membrane supports multiple vibration modes, providing a wider bandwidth for the imaging device. One example includes at least one piezoelectric element including two sub-elements and two terminals. Each subcomponent has a different center frequency and bandwidth, so when used in parallel, its own bandwidth is greater than any one subcomponent. Anatomical and Doppler imaging are performed over a larger bandwidth through electronic control and elevation focus control to increase sensitivity.

One example further includes each piezoelectric element exhibiting multiple vibration modes, enabling anatomical structure and Doppler imaging over a large bandwidth through electronic control and elevation focus control. Imaging can be performed by the transducer for low frequency imaging for abdominal or cardiac imaging. Likewise, imaging can be performed through the transducer for high-frequency imaging for musculoskeletal (MSK) or vascular imaging.

As mentioned previously, the transducer may have a large imaging surface or aperture and may need to operate over the entire aperture. The entire hole depends on the entire array of components or subcomponents. Under electronic control, the aperture size can be changed to include a smaller number of elements or sub-elements, and possibly reduced to a single sub-element. The smaller apertures are smaller imaging surfaces or sub-apertures and include a subset of the piezoelectric elements in the piezoelectric layer.

Referring to Figure 21, there is shown an imaging device (3408) having transmit operations (3409) and receive operations (3410) as indicated by arrows. The solid arrows in the transmit operation (3409) and the receive operation (3410) indicate the sub-elements and subsets of the piezoelectric elements (Fig. 1, 104) used in the operations in the arrow areas. The dashed arrows indicate which sub-elements and subsets of the piezoelectric elements are not used (Fig. 1, 104). The hole size (3412) indicates the portion of the imaging object (3415) that will be imaged as a result of the use of subelements and subsets. Selection and configuration of subelements and subsets may be electronically changed to define hole dimensions (3412).

Note that some sub-elements can be used for one operation (e.g. send, receive) and other sub-elements can be used for another operation (e.g. send, receive). There may be some overlap in the subelements used for each operation. The child elements can be the same for each operation. Sub-elements may further have simultaneous transmit and receive capabilities.

Two sub-elements can also be used to further broaden the bandwidth, where the sub-elements have different center frequencies and, when used simultaneously, will broaden the bandwidth when used in transmit or receive operations. The imaging device may be implemented using multiple sub-elements such that the combined bandwidth of the multiple sub-elements is greater than each sub-element.

Various types of imaging can be performed using an array of piezoelectric elements (Fig. 1, 104). For example, A-scan, B-scan, C-scan and Doppler modes can be performed. Other types of imaging that can be performed include pulsed Doppler and color Doppler. Additionally, Doppler processing can be performed in which some clutter rejection filtering occurs before digitization, such as programmable high-pass filtering, thus increasing the dynamic range of Doppler signals with high clutter levels. In one example, Doppler processing is performed on Doppler signals received from at least one piezoelectric element, and a low-noise amplifier performs programmable high-pass filtering on the received Doppler signals prior to digitization, and Further digital signal processing and beamforming.

In some examples, the elevation plane can be tilted and electronically focused to bring it closer to the optimal Doppler angle for better signal visualization. Figure 22 depicts an elevation angle (3604) defined by an elevation plane (3602) between a horizontal plane (3608) and a line of sight measured in a vertical plane. The imaged object (3606) can have better visualization depending on the elevation angle (3604) that can be modified to obtain the desired visualization.

High-quality Doppler imaging can have a high signal-to-noise ratio (SNR). SNR is a function of elevation angle (3604) shown in Figure 22. In one example, the elevation angle (3604) can be electronically adjusted for flow imaging. The elevation focus can be controlled in the elevation plane (3602) by adjusting the delay of the elements on the row. Note that the focused beam in the axial direction is controlled by adjusting the retardation of the element in the azimuthal direction. With independent delay control for elevation and azimuth, 3D beam steering can be performed to improve Doppler signal amplitude. In an example, the steering structure is used for beam steering capabilities in 3D space. In another example, a steering structure is used to electronically steer the beam in 3D space closer to the optimal Doppler angle for better signal visualization. In another example, the azimuth focus, elevation focus, and aperture size of the imaging device will be changed electronically.

Referring to Figure 23, the azimuth angle (3605) of the imaging device (3610) can be varied to produce a circular sector of field of view spanning up to 90 degrees in azimuth. This can be done simultaneously or independently of changing the aperture size (Fig. 21, 3412). Therefore, the delivery beam can be manipulated in 3D space, and anatomy and flow imaging can be performed in 3D space.

A row's components and subcomponents can be treated as separate, independent rows. A column's components and subcomponents can be treated as separate, independent columns. In some variations, columns and rows, or parts thereof, switch roles so that they are considered rows and columns, respectively.

Further configurations may include enabling corresponding receive amplifiers in receive mode or disabling individual receive amplifiers in receive mode, for example for use in B-mode anatomical imaging, color Doppler or PW flow imaging. Similarly, the configuration includes, for the imaging modes mentioned for the receive amplifier, enabling the corresponding transmit driver or a single transmit driver in transmit mode and disabling the corresponding transmit driver in receive mode. An example includes placing each piezoelectric element first in transmit mode and then in receive mode to receive echoes from the transmit mode, where the transmit power level, azimuth focus, elevation focus, beam in 2D or 3D space The aperture size of the manipulation and imaging device can be changed electronically.

The description of various embodiments of the present invention has been presented for purposes of illustration, but these descriptions are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the specific embodiments described. The terminology selected and used herein is intended to best explain the principles of specific embodiments, practical applications, or technical improvements over technologies found in the market, or to enable others skilled in the art to understand the specific embodiments disclosed herein.

For purposes of illustration, specific details set forth herein are provided in order to provide an understanding of what is disclosed herein. However, it will be apparent to those skilled in the art that the disclosure herein may be practiced without these details. Furthermore, those skilled in the art will recognize that examples of the disclosure herein may be implemented in a variety of ways, such as processes, apparatus, systems, apparatus, or methods on tangible computer-readable media.

Those skilled in the art will recognize that: (1) certain manufacturing steps may be optionally performed; (2) the steps may not be limited to the specific order listed here; (3) certain steps may be performed in a different order, including executed simultaneously.

The elements/components shown in the figures are illustrative of exemplary embodiments of the disclosure herein and are intended to avoid obscuring the disclosure herein. Reference in the specification to “one example,” “preferred example,” “an example,” or “example” means that a particular feature, structure, characteristic, or function described in connection with the example is included in at least one of the following examples, and may be More than one example. The appearances of the phrases "in an example," "in an example," or "in an example" in various places in the specification are not necessarily all referring to the same example or examples. The terms "includes," "includes," "contains," and "has" are understood to be open-ended terms and any listings are examples and are not meant to be limited to the items listed. Any headings used herein are for organizational purposes only and shall not be used to limit the scope of the specification or claims. In addition, certain terms are used in various places in the specification for the purpose of explanation and should not be construed as limiting.

100: Imaging device 102: Piezoelectric transducer 104: Piezoelectric element 106:Send channel 108:Receive channel 109:Control circuit 110:Computing device 111:Power supply and battery 210: Pressure wave 214:Heart 216:Computing device 218: Communication channel 220:Display device 322:Coating 324:Controller 326: Graphics processing unit (GPU) 328:Analog Front End (AFE) 330: Acoustic absorbing layer 332: Communication unit 334:port 336: Memory 338:Battery 540: Transceiver substrate 542: Line N 544:M column 648:Picture frame 650:Scan line 752:Signal 754:Composite signal 801:Box 1056:LNA 1058: Programmable Gain Amplifier (PGA) 1060: Bandpass filter 1062:Analog-to-digital converter (ADC) 1064: Demodulation unit 1166: Operational amplifier 1201: Elevation plane 1202: Azimuth plane 1268: Fast power-on bias circuit 1370:Substrate layer 1372:Substrate layer 1373: Grooves or grooves 1374:membrane 1376: cavity 1399:Solid area 1401:Pillar 1402:Pillar 1403:Coating 1404: Acoustic absorbing layer 1405:Wire 1406:membrane 1407:Electrode 1408:Wire 1409: Piezoelectric materials 1410: Second electrode 1411:Substrate 1414:Pillar 1415:Pillar 1417:ASIC 1420:Transducer 1578: Bottom electrode 1680: Piezoelectric layer 1782:Top electrode 1783: Top electrode conductor 1800: Piezoelectric element 1878:Second electrode 1880: Piezoelectric layer 1882:First electrode 1886:First Conductor 1890:Second Conductor 1900: Piezoelectric element 1923: Piezoelectric elements 1925-1:Substrate 1925-2:Substrate 1927: Membrane 1929: Bottom electrode 1931:Conductor 1933: Piezoelectric layer 1935: Top electrode 1937:Conductor 1970:Substrate layer 1972:Substrate layer 1976: cavity 1978-1: First bottom electrode 1978-2: Second bottom electrode 1980: Piezoelectric layer 1982:First Electrode 1984-1:Conductor 1984-2:Conductor 1984-3:Conductor 1996-1: Subcomponent 1996-2: Subcomponent 1997:Trench 2100:Transducer 2102-1: Pulse 2102-2: Pulse 2102-3: Pulse 2102-4: Pulse 2104:Scan line 2108:Picture frame 2110:Colored window 2112:Send beam 2114:Receive beam 2116: Flow sensitive area 2901-1: Wavefront 2901-2: Wavefront 2902-1:Area 2902-2:Area 2903-1:Area 2903-2:Area 2903-3:Area 2905-1: Membrane 2905-2: Membrane 2997-1:Subcomponent 2997-2:Subcomponent 2998-1:Trench 2998-2:Trench 2998-3:Trench 3000-1:Link 3000-2:Link 3000-3:Link 3001:Coupler 3002:Substrate 3200:ASIC controller 3300:MEMS structure 3408: Imaging device 3409:Send operation 3410:Receive operation 3412: Hole size 3415: Imaging object 3602: Elevation plane 3604:elevation angle 3605:azimuth angle 3606: Imaging object 3608: Horizontal plane 3610: Imaging device 3901-1: Cavity 3901-3: Cavity 3905-1: Membrane 3905-2: Membrane 3998-1:Trench 3998-2:Trench 3998-3:Trench 3999-1:Trench 3999-2:Trench 3999-3:Trench 4101:First beam 4102:Second beam 4103:The third beam 4104:The fourth beam 102-1:Transducer array 102-2:Transducer array 102-3:Transducer array 1374-1: Membrane 1374-2: Membrane 1784-1: Bottom electrode conductor 1784-2: Bottom electrode conductor 1790-1:Through hole 1790-2:Through hole 546-1: Temperature sensor 546-2: Temperature sensor 546-3: Temperature sensor 546-4: Temperature sensor

The accompanying drawings illustrate various examples of the principles described herein and are a part of the specification. The examples given are for illustration only and do not limit the scope of the claimed patent.

Figure 1 shows a block diagram of an imaging device for anatomical and flow imaging according to an example of the principles described herein.

Figure 2 shows a diagram of a portable imaging system for anatomy and flow imaging according to an example of the principles described herein.

Figure 3 shows a schematic diagram of an imaging device with imaging capabilities according to an example of the principles described herein.

Figure 4 shows a side view of an example bending transducer array in accordance with the principles described herein.

Figure 5 shows a top view of an example transducer in accordance with the principles described herein.

6A illustrates a perspective view of a scan line of an imaging device and a frame in accordance with an example of principles described herein.

Figure 6B shows the azimuth (xa), elevation (ya) and axial/depth (za) directions.

Figure 6C shows that the beam focus and steering changes with the delay of the elements on the line.

Figure 6D shows a two-dimensional matrix of elements in which the relative delays along the rows are changed.

Figure 7 illustrates the formation of scan lines according to an example of the principles described herein.

8 shows a flowchart of a method for selectively changing the number of channels of an imaging device according to an example of the principles described herein.

Figure 9 illustrates an example receive channel in accordance with the principles described herein.

Figure 10 shows a simplified schematic diagram of a low-noise amplifier (LNA) of the receive channel according to an example of the principles described herein.

Figure 11 shows a circuit diagram of an example fast power-up bias circuit in accordance with the principles described herein.

Figure 12 illustrates the fabrication of an example piezoelectric element according to the principles described herein.

Figure 13 illustrates the fabrication of an example piezoelectric element according to the principles described herein.

Figure 14 illustrates the fabrication of an example piezoelectric element according to the principles described herein.

Figure 15 illustrates the fabrication of an example piezoelectric element according to the principles described herein.

Figure 16 illustrates the fabrication of an example piezoelectric element in accordance with the principles described herein.

Figure 17A illustrates component construction for isolation to reduce crosstalk between adjacent components.

Figure 17B illustrates component construction for isolation to reduce crosstalk between adjacent components.

Figure 17C shows a cross-sectional view of a transducer element coupled to a corresponding application specific integrated circuit (ASIC) with at least transmit driver and receive amplifier electronics in the ASIC.

Figure 18 shows a top view of a bottom electrode arranged on a substrate layer and above a membrane according to an example of the principles described herein.

Figure 19A shows a schematic diagram of a piezoelectric element according to another example of the principles described herein.

Figure 19B shows a symbolic representation of the piezoelectric element of Figure 19A according to an example of the principles described herein.

Figure 19C shows a cross-sectional view of an example piezoelectric element in accordance with the principles described herein.

Figure 19D shows a cross-sectional view of two sub-elements arranged on a substrate according to an example of the principles described herein.

Figure 19E shows a cross-sectional view of two adjacent elements showing details of the piezoelectric layer, conductors and isolation means according to an example of the principles described herein.

Figure 19F shows a cross-sectional view of two adjacent elements showing isolation details to minimize crosstalk, according to an example of the principles described herein.

Figure 19G shows a cross-sectional view of two adjacent elements showing isolation details to minimize crosstalk, according to an example of the principles described herein.

Figure 19H shows a cross-sectional view of two adjacent elements showing isolation details to minimize crosstalk, according to an example of the principles described herein.

Figure 19I shows a piezoelectric element using a bending mode of operation according to an example of the principles described herein.

Figure 20A shows an example scan line showing the entirety of a pulse in accordance with the principles described herein.

Figure 20B shows an imaging frame with multiple scan lines, each line showing multiple samples, according to an example of the principles described herein.

Figure 21 illustrates transmit and receive operations using sub-elements and subsets to obtain images according to an example of the principles described herein.

Figure 22 shows a tilted and focused elevation according to an example of the principles described herein.

Figure 23 illustrates electronically changing azimuthal focus according to an example of principles described herein.

Figure 24 illustrates flow sensitive regions in the Doppler sample volume.

Throughout the drawings, the same reference numbers refer to similar, but not necessarily identical, elements. The drawings are not necessarily to scale and the dimensions of certain portions may be exaggerated to more clearly illustrate the examples shown. Furthermore, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

Domestic storage information (please note in order of storage institution, date and number) without Overseas storage information (please note in order of storage country, institution, date, and number) without

100: Imaging device

102: Piezoelectric transducer

104: Piezoelectric element

106:Send channel

108:Receive channel

109:Control circuit

110:Computing device

111:Power supply and battery

Claims (20)

An imaging device including: a transducer; A two-dimensional (2D) array of piezoelectric elements arranged in rows and columns on the transducer, each piezoelectric element having at least two terminals, each piezoelectric element being connected to each adjacent piezoelectric element. Physical isolation of electrical components to reduce crosstalk; A first row of the array of piezoelectric elements, each piezoelectric element having a first top electrode connected to a corresponding receive amplifier, each of the piezoelectric elements is to be electronically programmed, as linked together to form a first column, and A second row of the piezoelectric element array, each piezoelectric element having a second top electrode connected to a corresponding transmit amplifier, each of the piezoelectric elements is to be electronically programmed, as linked together to form a second row of the same; where, The electronically programmed connections of the piezoelectric elements enable the connection of any number of piezoelectric elements in a row. The imaging device as claimed in claim 1, wherein: Row components and subcomponents are controlled as separate, independent rows. The imaging device as claimed in claim 1, wherein: Each piezoelectric element exhibits multiple vibration modes, enabling anatomical structure and Doppler imaging over a large bandwidth through electronic control and focus control in an elevation plane. The imaging device as claimed in claim 1 further includes: At least one sub-aperture including at least one row of piezoelectric elements, wherein each piezoelectric element includes two sub-elements, each sub-element selected to operate with programmable transmit and receive functions such that upon receiving a second Simultaneity of sub-elements - The first sub-element can transmit simultaneously, and each sub-element switches between transmit mode and receive mode. An imaging device including: a transducer; a two-dimensional (2D) array of piezoelectric elements arranged in rows and columns on the transducer, each piezoelectric element having at least two terminals; at least a first row of piezoelectric elements, each piezoelectric element having a first top electrode connected to a corresponding receive amplifier or a transmit driver under programming control; and at least a second row of piezoelectric elements, each piezoelectric element having a first top electrode connected under programming control to a corresponding receive amplifier or a transmit driver, the piezoelectric elements being programmed to transmit and then receive, or programmed to send and receive simultaneously; where, The connections of the piezoelectric elements in the columns are electronically programmed to achieve the connection of an arbitrary number of piezoelectric elements in each column. The imaging device as claimed in claim 5, wherein: Column components and subcomponents are controlled as separate, independent columns. The imaging device as claimed in claim 5, wherein: At least one piezoelectric element includes two sub-elements and two terminals, each sub-element having a different center frequency and bandwidth, so that when used in parallel, the piezoelectric element itself exhibits a wider frequency range than either sub-element. bandwidth. The imaging device as claimed in claim 5, wherein: Each piezoelectric element includes two sub-elements for CW Doppler imaging, in which at least a first piezoelectric element is placed in a transmit mode and a second piezoelectric element is simultaneously placed in a receive mode. The imaging device as claimed in claim 8, wherein: For pulse wave (PW) Doppler imaging, at least the first piezoelectric element is placed in transmit mode and switched to receive mode. The imaging device as claimed in claim 5, wherein: Each piezoelectric element is first placed in transmit mode and then in receive mode to receive echoes from the transmit mode, where the transmit power level, an azimuth focus, an elevation focus, beam steering in 2D or 3D space, and An aperture size of the imaging device can be changed electronically. The imaging device as claimed in claim 5, wherein: Adjusts a desired azimuthal depth of focus for the curvature in the transducer. The imaging device as claimed in claim 5, wherein: An elevation focus is electronically adjusted to include a delay adjustment to compensate for curvature in the transducer. An imaging device including: an application specific integrated circuit (ASIC); A transducer, the transducer includes an array of piezoelectric elements formed on a substrate, each piezoelectric element includes: At least one film suspended relative to the substrate; At least one bottom electrode, the at least one bottom electrode is disposed on the membrane; At least one piezoelectric layer, the at least one piezoelectric layer is disposed on the bottom electrode; At least one top electrode disposed on the at least one piezoelectric layer, wherein adjacent piezoelectric elements are acoustically isolated from each other; and A controller, the controller is connected to the ASIC, wherein the controller implements an imaging mode through the following steps: Select a first plurality of piezoelectric elements from the piezoelectric element array to transmit signals to form a transmission channel associated with the imaging mode; Selecting a second plurality of piezoelectric elements from the array of piezoelectric elements to receive signals to form a receiving pass channel associated with the imaging mode; and A frame is formed from a plurality of scan lines obtained according to the imaging mode, wherein after the frame is completed, the imaging mode remains the same or switches to a different mode. The imaging device as claimed in claim 13, wherein: The ASIC is attached to the substrate and electrically connected to enable anatomical and Doppler flow imaging, with each piezoelectric element exhibiting a plurality of vibration modes. The imaging device as claimed in claim 13, wherein: At least one membrane is attached to the ASIC in a backward orientation, with a cavity facing an imaging target. The imaging device as claimed in claim 13, wherein: At least one membrane is coupled to the ASIC in a forward transmit direction, with a cavity facing the ASIC, and the at least one membrane transmits and receives from a front side. The imaging device as claimed in claim 13, wherein: Transmit elevation focus electronically. The imaging device as claimed in claim 13, wherein: Electronic focusing is achieved by the ASIC by changing the relative delay of a beam sent by a piezoelectric element in a row. The imaging device as claimed in claim 13, wherein: A digital register in the ASIC is controlled by the controller, where the required transmit elevation focal depth is sent to the ASIC. The imaging device as claimed in claim 13, wherein: A desired azimuthal depth of focus is sent from the controller to the ASIC, where the ASIC sets a relative delay of the piezoelectric element.

Images