CN108175446B - Ultrasonic transceiver probe, ultrasonic transduction array device and fetal heart monitor - Google Patents
Ultrasonic transceiver probe, ultrasonic transduction array device and fetal heart monitor Download PDFInfo
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- CN108175446B CN108175446B CN201810074548.9A CN201810074548A CN108175446B CN 108175446 B CN108175446 B CN 108175446B CN 201810074548 A CN201810074548 A CN 201810074548A CN 108175446 B CN108175446 B CN 108175446B
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/02—Measuring pulse or heart rate
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0866—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving foetal diagnosis; pre-natal or peri-natal diagnosis of the baby
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0883—Detecting organic movements or changes, e.g. tumours, cysts, swellings for diagnosis of the heart
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4444—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device related to the probe
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
Abstract
The invention discloses an ultrasonic transceiver probe which comprises a substrate, an extraction electrode, a first conductive layer and a second conductive layer; attaching the first conductive layer on a first surface and attaching the second conductive layer on a second surface opposite to the first surface; the second conductive layer comprises a plurality of conductive subareas, and the plurality of conductive subareas are distributed in an insulated manner; the extraction electrode comprises a first extraction electrode and a second extraction electrode; the first extraction electrode is electrically connected with the first conductive layer; the second extraction electrode comprises a plurality of second extraction electrodes, and the second extraction electrodes are respectively connected with the plurality of conductive subareas. According to the invention, the conductive layer on the second surface of the large-area ultrasonic transceiver probe is designed to be separated into a plurality of conductive subareas, so that the large-area ultrasonic transceiver probe can emit ultrasonic beams with large cross sections to enlarge the detection coverage area, and when receiving an ultrasonic feedback signal, the plurality of conductive subareas independently receive the feedback signal.
Description
Technical Field
The invention relates to the field of electronic devices, in particular to an ultrasonic transceiver probe, an ultrasonic transduction array device and a fetal heart monitor.
Background
Fetal heart beat can be monitored before birth to detect whether the fetus is abnormal. Ultrasonic detection of fetal heart rate requires positioning to the heart position to improve the sensitivity of detecting heart beats. But since the fetal heart position in the uterus is unknown, the fetal heart position has to be found by moving the ultrasound transducer frequently. The existing ultrasonic transducer is inconvenient to apply to fetal heart detection because the probe of the ultrasonic transceiver is small and the cross-sectional area of the emitted ultrasonic beam is small, so that coverage cannot be realized in the uterus range. Ultrasonic detection of fetal heart rate preferably uses an ultrasonic beam with a large cross-sectional area to cover the heart or to easily locate the beating heart. The large cross-sectional area of the ultrasonic beam is generated by the large area of the ultrasonic transceiver probe, the cross-section of the ultrasonic beam is approximately equal to the ultrasonic transceiver probe area within a specified distance, and spreads farther. This phenomenon is in the near field region, and the ultrasonic beam is divergent over a large distance. The region where the ultrasonic beam does not spread is called a near field region, and is more suitable for fetal heart detection when the heart is in the near field region. Because the ultrasound signals reflected by the heart must spread to a large angle when the ultrasound beam area covers the heart, the heart is small and the heart wall is curved, the reflected ultrasound signals appear scattered, and the scattered reflected ultrasound signals return to all areas of the large area ultrasound transceiver probe for detection. However, in order to protect the fetus, the wavelength of the ultrasonic waves used for fetal heart detection is small (1.5 mm at 1MHz and 0.75mm at 2 MHz), the reflected ultrasonic wave signal that enters perpendicularly to the probe surface of the ultrasonic transceiver is strongest, but elsewhere, the ultrasonic beam reflected by the heart is oblique, the signal becomes weak, and every point near the probe area of the ultrasonic transceiver is different and the difference is far beyond the wavelength. The strongest signal in the optimal position can be transmitted to the probe areas of the ultrasonic transceiver with weak signals and different phases, so that the signal in the optimal position is weakened, and the problem of accurately detecting the fetal heartbeat cannot be solved by simply increasing the area of the probe of the ultrasonic transceiver.
Accordingly, there is a need in the art for improvement.
Disclosure of Invention
The invention mainly aims to provide an ultrasonic transceiver probe, which aims to solve the technical problem that an ultrasonic transceiver probe in the conventional fetal heart monitor cannot accurately detect a fetal heart.
The invention provides an ultrasonic transceiver probe which comprises a substrate, an extraction electrode, a first conductive layer and a second conductive layer;
attaching the first conductive layer to a first surface of the substrate, and attaching the second conductive layer to a second surface opposite to the first surface;
the second conductive layer comprises a plurality of conductive subareas, and the plurality of conductive subareas are distributed in an insulated manner;
the extraction electrode comprises a first extraction electrode and a second extraction electrode; the first extraction electrode is electrically connected with the first conductive layer; the second extraction electrode comprises a plurality of second extraction electrodes, and the second extraction electrodes are respectively connected with the plurality of conductive subareas.
Preferably, the first and second conductive layers are formed by coating a piezoelectric material including one of a piezoelectric polymer, a piezoelectric ceramic, and a piezoelectric crystal on the surface of the substrate.
Preferably, the piezoelectric polymer comprises one or two of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer and polyvinylidene fluoride containing air.
The invention also provides an ultrasonic transduction array device, which comprises: the ultrasonic transceiver probe also comprises an ultrasonic driving device and a driving circuit;
one end of the driving circuit is connected with the ultrasonic driving device, the other end of the driving circuit is connected with each conductive subarea of the ultrasonic transceiver probe, and each conductive subarea respectively receives a driving signal sent by the ultrasonic driving device and generates an ultrasonic signal.
Preferably, the ultrasonic transducer array device comprises a plurality of first anti-parallel diode pairs, and the plurality of first anti-parallel diode pairs are respectively connected in series between each conductive subarea and the ultrasonic driving device; the driving signal generated by the ultrasonic driving device under the action of the driving voltage acts on each conductive subarea through a plurality of first anti-parallel diode pairs simultaneously to generate ultrasonic signals and emit the ultrasonic signals, and the ultrasonic feedback signals received by each conductive subarea are respectively prevented from returning to the ultrasonic driving device by the connected first anti-parallel diode pairs.
Preferably, the ultrasonic transducer array device further comprises an ultrasonic feedback signal calculation circuit, wherein the ultrasonic feedback signal calculation circuit is connected between each conductive subarea and each first antiparallel diode pair, receives an ultrasonic feedback signal received by each conductive subarea and calculates the magnitude.
Preferably, the ultrasonic feedback signal calculation circuit includes a plurality of signal processing branches, each signal processing branch outputs an ultrasonic feedback signal received by each conductive subarea, and the azimuth of the ultrasonic feedback signal with the strongest signal strength is distinguished according to the strength of the ultrasonic feedback signal.
Preferably, the signal processing branch comprises a resistor and a signal amplifier connected in series; each of the resistors is connected in series between each of the signal amplifiers and each of the conductive subregions.
Preferably, the ultrasonic transducer array device further comprises a plurality of second antiparallel diode pairs, one end of each second antiparallel diode pair is connected between the resistor and the signal amplifier, and the other end is grounded.
The invention also provides a fetal heart rate instrument which comprises the ultrasonic transduction array device.
Preferably, the fetal heart rate monitor further comprises a housing, the ultrasonic transceiver probe is close to the inner wall of the housing by the conductive layer on the first surface, and the ultrasonic transceiver probe is in a plane shape or an arc-shaped bending shape.
Preferably, the thickness of the shell is 1/4 wavelength of the sound wave of the shell material; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance.
Preferably, the thickness of the shell is N times of half wavelength of sound wave of the shell material, n=0, 1, 2, 3 or 4; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance.
The invention has the beneficial technical effects that: according to the invention, the conducting layer on the second surface of the large-area ultrasonic transceiver probe is designed to be separated into a plurality of conducting subareas distributed in an array, the ultrasonic driving device can synchronously drive the plurality of conducting subareas under the driving of driving voltage, so that the large-area ultrasonic transceiver probe can emit large-cross-section ultrasonic beams to enlarge the coverage area, and accurate positioning is realized; and when receiving the ultrasonic feedback signals, the plurality of conductive subareas independently receive the feedback signals, so that the technical problem of mutual interference of the received feedback signals in different receiving areas of the integrated large-area ultrasonic transceiver probe is solved, and the detection precision is improved.
Drawings
FIG. 1 is a schematic longitudinal section of an ultrasonic transceiver probe according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the front structure of an ultrasonic transceiver probe according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an ultrasonic transducer array device according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a path of an ultrasonic reflected wave reaching each conductive subarea of an ultrasonic transducer array device according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the path of an ultrasonic reflected wave to each conductive subarea of an ultrasonic transducer array device according to another embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating the operation of an antiparallel diode pair according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of the propagation state of an ultrasonic beam emitted by a circular ultrasonic transceiver probe according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of the waveform state of an ultrasonic beam emitted by a circular ultrasonic transceiver probe according to an embodiment of the present invention;
FIG. 9 is a schematic diagram showing the waveform state of an ultrasonic beam emitted from a planar ultrasonic transceiver probe according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of the structure of an ultrasonic transceiver probe according to an embodiment of the present invention;
fig. 11 is a schematic structural view of an ultrasonic transceiver probe according to another embodiment of the present invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, an ultrasonic transceiver probe according to an embodiment of the present invention includes a substrate 1, an extraction electrode, a first conductive layer, and a second conductive layer;
attaching the first conductive layer to a first surface of the substrate 1, and attaching the second conductive layer to a second surface opposite to the first surface;
the second conductive layer comprises a plurality of conductive subareas 2, and the plurality of conductive subareas 2 are distributed in an insulated manner;
the extraction electrode comprises a first extraction electrode and a second extraction electrode; the first extraction electrode is electrically connected with the first conductive layer; the second extraction electrodes comprise a plurality of second extraction electrodes, and the plurality of second extraction electrodes are respectively and electrically connected with the plurality of conductive subareas 2.
As shown in fig. 2, in the embodiment of the invention, a conductive layer on a second surface of a large-area ultrasonic transceiver probe is isolated into a plurality of conductive subareas 2, a plurality of conductive subareas 2 arranged in an array are integrated on a substrate 1, a plurality of sensors distributed in an array are formed by the conductive layer on the integrated first surface, and an ultrasonic driving device can synchronously drive the plurality of conductive subareas 2 under the driving of driving voltage, so that the large-area ultrasonic transceiver probe can emit a large-cross-section ultrasonic beam to enlarge a coverage area, and accurate positioning is realized; and when receiving the ultrasonic feedback signals, the plurality of conductive subareas 2 independently receive the feedback signals, so that the technical problem of mutual interference of the received feedback signals in different receiving areas of the large-area ultrasonic transceiver probe is solved, and the detection precision is improved. For example, the ultrasonic transceiver probe of the present embodiment is a large-area substrate on which 9 or 12 grid-like conductive sub-areas 2 are integrated and arranged in series and independent of each other. In other embodiments of the present invention, the arrangement, shape, pattern and number of the conductive sub-regions 2 may be designed according to actual needs.
Further, the first conductive layer and the second conductive layer of the ultrasonic transceiver probe of the present embodiment are formed by coating a piezoelectric material including one of a piezoelectric polymer, a piezoelectric ceramic, and a piezoelectric crystal on the substrate 1.
Compared with piezoelectric ceramics or piezoelectric crystals, the piezoelectric polymer has low cost, so the piezoelectric polymer is preferably used as a coating material of the first conductive layer and the second conductive layer of the ultrasonic transceiver probe in the embodiment, so that the manufacturing cost of the large-area ultrasonic transceiver probe is reduced. One or two of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene copolymer and polyvinylidene fluoride containing air are preferable in this embodiment.
Referring to fig. 3, the present invention also provides an ultrasonic transducer array apparatus comprising: the ultrasonic transceiver probe also comprises an ultrasonic driving device 3 and a driving circuit;
one end of the driving circuit is connected with the ultrasonic driving device 3, the other end of the driving circuit is connected with each conductive subarea 2 of the ultrasonic transceiver probe, and each conductive subarea 2 respectively receives the driving signal sent by the ultrasonic driving device 3 and generates an ultrasonic signal.
In the ultrasonic transducer array device of this embodiment, when transmitting the driving signal, the ultrasonic driving device 3 drives each of the conductive subareas 2 of the ultrasonic transceiver probe through the driving circuit simultaneously, and the ultrasonic transceiver probe transmits the ultrasonic signal outwards as a whole, so as to increase the effective cross-sectional area of the ultrasonic beam transmitted by the ultrasonic transceiver probe and increase the coverage area of the ultrasonic signal, so as to solve the problem of difficult positioning.
Further, the ultrasonic transducer array device comprises a plurality of first anti-parallel diode pairs 4, and the plurality of first anti-parallel diode pairs 4 are respectively connected in series between each conductive subarea 2 and the ultrasonic driving device 3; the driving signal generated by the ultrasonic driving device 3 under the action of the driving voltage acts on each conductive subarea 2 through a plurality of first anti-parallel diode pairs 4 at the same time to generate an ultrasonic signal, the ultrasonic signal is emitted through an ultrasonic transceiver probe, and the ultrasonic feedback signal received by each conductive subarea 2 is prevented from returning to the ultrasonic driving device 3 by the connected first anti-parallel diode pairs 4.
In the ultrasonic transducer array device of this embodiment, when receiving the feedback signal, each of the conductive subregions 2 is made into an independent feedback signal receiving region by the switching circuit formed by the first antiparallel diode pair 4, and the first antiparallel diode pair 4 of this embodiment includes two antiparallel connected diodes, as shown in fig. 6, with a peak voltage of 0.7V, which is different from the structure of a conventional diode. In this embodiment, each of the conductive sub-areas 2 is driven by the ultrasonic driving device through the first anti-parallel diode pair 4 respectively, as shown in fig. 3, which illustrates a limited number of connection relations, and each of the conductive sub-areas 2 of this embodiment is connected to the first anti-parallel diode pair 4, and there is no difference between the first anti-parallel diode pair 4 to which the curved ultrasonic transceiver probe or the planar ultrasonic transceiver probe is connected. The driving voltage range of the ultrasonic transceiver probe is 10-100V, the driving frequency is MHZ, and the impedance of the ultrasonic driving device is low. In the driving pulse period, when the driving voltage is zero, the current is zero, the first antiparallel diode pair 4 has very high impedance, so that each conductive subarea 2 is disconnected from the ultrasonic driving device, when receiving the feedback signal, the feedback signal received by each conductive subarea 2 must be disconnected from the ultrasonic driving device, because the low impedance absorbs or weakens the received feedback signal, and the feedback signal received by each conductive subarea 2 must be isolated from the feedback signals received by other conductive subareas 2, so that the feedback signal can be effectively detected. As shown in fig. 6, the voltage-current characteristics of the individual diodes are: when a forward voltage (from the arrow tail to the head) is applied, a current flows in the direction of the arrow when the forward voltage exceeds 0.7V, but a forward current of less than 0.7V does not generate a current. But when a voltage is applied in the opposite direction (from arrow to tail direction) no current flows. The first antiparallel diode pair 4 is formed by connecting two diodes in parallel and reversely, the ultrasonic wave beam which simultaneously reaches the transmitting mode according to the voltage-current characteristics has a large cross section area, and in the receiving mode, feedback signals received by the conductive subareas 2 are not interfered with each other, and are not interfered by voltage pulses of the ultrasonic driving device, so that the reliability of detection signals is improved.
The substrate 1 of the ultrasonic transceiver probe of the present embodiment is PVDF, a conductive layer is uniformly coated on a first surface of PVDF as shown in fig. 3, and an electrode of the conductive layer is grounded; the conductive layer on the second surface is divided into a plurality of areas, which are separated by a dotted line and independently controlled, as shown in fig. 4. When the ultrasonic transceiver probe is used as a transmission mode, all the conductive sub-areas 2 are driven simultaneously, activated as one single large-area conductive area, the outline of the emitted ultrasonic beam has a large cross-sectional area, and when the ultrasonic transceiver probe is bent for use, the ultrasonic beam of a larger cross-sectional area is propagated. When the ultrasonic transceiver probe is used as a receiving mode, the conductive area is isolated into a plurality of conductive subareas 2, each conductive subarea 2 receives ultrasonic feedback signals respectively, and the largest feedback signal is selected as a detection signal, so that the detection accuracy is improved. In the transmit mode, the ultrasound signals enter the fetal heart directly from the ultrasound transceiver probe surface. Since the fetal heart is much smaller than the size of the ultrasound transceiver probe, the reflected ultrasound signals diffuse or scatter in the heart, and the scattered ultrasound is modeled as a point source of radiation. As shown in fig. 5, the distance of the transmission route a of the conductive subregion 2 that arrives perpendicularly from the heart position is shortest, while the transmission distance of the route B having a planar pinching with the conductive subregion 2 is larger than that of the route a. The feedback signal of the transmission line with the shortest distance is strongest, and the phase of the received signal in the same conductive subarea 2 also affects the strength of the feedback signal, as shown in fig. 4, the feedback signal received by the conductive subarea 2 corresponding to the hatched area is strongest.
The effect of the phase effect on the feedback signal, as shown in fig. 5, the angle of the ultrasonic wave from the heart to the cross section of the ultrasonic transceiver probe along the straight line path a to the surface of the ultrasonic transceiver probe is almost 90 degrees, and the distance from the heart to the ultrasonic transceiver probe is the shortest. In fig. 5, the wavelength λ region is the phase plane of spherical ultrasonic waves, and the solid line curve and the dotted line curve represent the positive and negative phases of sound pressure waves, respectively. The feedback signal received at the same conductive sub-area 2 is the sum of the sound pressures received at all points of the conductive sub-area 2. The high phase of the sound pressure phase is almost constant in the region, but the low phase varies with the change of the positive charge and varies very much. In the low phase, the positive and negative sound pressures cancel each other out and become very weak, so the signal from the low phase is much weaker than the signal from the high phase. As described above, the intensity of the feedback signal received by each conductive sub-region 2 is different, for example, the feedback signal received by one conductive sub-region 2 is strongest, the feedback signals received by other conductive sub-regions 2 are weaker, and when all conductive sub-regions 2 are electrically connected together, the feedback signal with the strongest intensity spreads to the conductive sub-regions 2 with weaker feedback signals, resulting in weakening of all the feedback signals.
Further, the ultrasonic transducer array device further includes an ultrasonic feedback signal calculating circuit 5, where the ultrasonic feedback signal calculating circuit 5 is connected between each of the conductive subregions 2 and each of the first antiparallel diode pairs 4, receives an ultrasonic feedback signal received by each of the conductive subregions 2, and calculates the magnitude thereof.
When receiving the feedback signal, the feedback signal received by each conductive subarea 2 is output to the outside through the ultrasonic feedback signal calculation circuit 5. Further, the ultrasonic feedback signal calculating circuit 5 includes a plurality of signal processing branches, each of which outputs the ultrasonic feedback signal received by each of the conductive subregions 2, and discriminates the orientation of the ultrasonic feedback signal with the strongest signal strength according to the strength of the ultrasonic feedback signal.
Further, the signal processing branch comprises a resistor 50 and a signal amplifier 51 connected in series; each of the resistors 50 is connected in series between each of the signal amplifiers 51 and each of the conductive subregions 2. The resistors 50 such as R1 and R2 are fed back to the corresponding signal amplifiers 51, the resistance value of the resistor 50 is small, and the feedback signal can smoothly pass through to be output to the outside through the signal amplifiers 51 and display the corresponding detection result.
Further, the ultrasonic transducer array device further comprises a plurality of second anti-parallel diode pairs 52, and one end of each second anti-parallel diode pair 52 is connected between the resistor 50 and the signal amplifier 51, and the other end is grounded.
The second antiparallel diode pair 52 of this embodiment acts to suppress high voltage pulses below 0.7V to avoid the drive pulses of the ultrasonic drive device from compromising the function of the high gain amplifier. The second anti-parallel diode pair 52 of the present embodiment has a very high impedance and the received signal is less than ±0.7v, so the second anti-parallel diode pair 52 does not affect the signal amplifier 51 to receive the feedback signal. The output signal of the signal amplifier 51 of the present embodiment is comprehensively processed by a doppler method or a pulse timing method and other specific algorithms to detect the rate motion of the heart and determine whether the fetal heart is normal or abnormal.
The invention also provides a fetal heart rate instrument which comprises the ultrasonic transduction array device. Further, the fetal heart rate monitor further comprises a shell, the ultrasonic transceiver probe is close to the inner wall of the shell through the conducting layer on the first surface, and the ultrasonic transceiver probe is in a plane shape or an arc-shaped bending shape.
The assembly shape of the ultrasonic transceiver probe of this embodiment may be planar or curved, but it is sufficient that the heart is within the near-field distance range of the ultrasonic transceiver probe transmitting the ultrasonic beam. The fetal heart monitor of this embodiment has a housing that is the outer structure of the ultrasonic transceiver probe to prevent external interference from mechanical, chemical or electromagnetic sources, but the thickness and material of the housing can affect the performance of the ultrasonic transceiver probe. From an acoustic performance perspective, the design of the thickness of the housing is related to a specific fraction of the wavelength in the material. The bandwidth may be modified to be wider or narrower depending on the relationship with wavelength. When pulse timing measurements are used to detect fetal heart motion, sharp pulses need to be used, requiring a wide bandwidth. When doppler shift is used, long pulses (pulses) and narrow bandwidths are required due to the high sensitivity. In other embodiments of the invention, the fetal heart monitor has no housing and the ultrasonic transceiver probe is directly used as the detection contact surface.
As shown in fig. 7, the ultrasonic beam emitted from the ultrasonic transceiver probe propagates directly from the ultrasonic transceiver probe, but at a critical point x=x in the near field region C N The ultrasonic beam begins to spread, in the far field region DIn a diffused state. In this diffusion region, the Sound Pressure Level (SPL) is maximum on the coordinate axis, and the distribution function in the direction perpendicular to the coordinate axis is weak. The distribution of SPL is determined by frequency, transducer size and propagation speed, given by a simple equation for far field distribution. Angle theta 1/2 Sound pressure at the position becomes 50%, θ 1/2 =arcsi n (1.1 λ/pi a) ≡0.35 λ/a, (λ is wavelength, 2a is diameter of the ultrasonic transceiver probe), for example, diameter 2a=12 mm, λ=1.5 mm (1 MHz), θ 1/2 =5.0 degrees, or λ=0.75 millimeters (2 MHz), θ 1/2 =2.5 degrees (2 MHz). However, even if the ultrasonic beam spreads, the cross-sectional diameter of the ultrasonic beam is not large enough, and it is difficult to find the heart position by moving the ultrasonic transceiver probe. But the ultrasound beam in the near field region C will not spread out, the outline or size of the ultrasound beam is about the same or slightly smaller than the size of the ultrasound transceiver probe, and at the critical point x=x N Minimum at a distance greater than x=x N The distribution state of the ultrasonic beam in the near field region C, which starts to diverge later, shows a complex pattern, and cannot be expressed by a simple equation, which is called near field distribution. FIG. 8 shows the waveform distribution of the ultrasonic beam of a circular ultrasonic transceiver probe, with a null at the center of the middle region of the near field, the null not being near the ultrasonic transceiver probe, preferably designed as X N Greater than the distance of the ultrasonic transceiver probe from the heart, as shown, when x=x N Size ratio x=x of ultrasonic beam at/3 N The size of the ultrasonic beam at/2 is large, x=x N Minimum time, and X > X N At this time, the ultrasonic beam starts to spread.
Small-sized circular ultrasonic transceiver probe (2a=12 mm), passing X between near field region to far field region N ＝a 2 The transition is carried out, for example, by 24mm diameter (1 MHz) and 48mm diameter (2 MHz). In the far field region, the ultrasound beam spreads according to the far field equation, at the critical point x=x N The ultrasonic wave is the smallest in size, about 40% of the cross-sectional area of the ultrasonic transceiver probe, and is called the beam waist or focal point. Taking the spread of an ultrasonic beam of 12mm diameter as an example, an ultrasonic transceiver probe is 5 degrees (1 MHz) or 2.5 degrees (2 MHz) at a distance from the ultrasonic transceiver50% of the diameter of the ultrasound beam at 10cm of the probe was converted to 17.6mm (1.0 MHz) and 8.8mm (2.0 MHz).
In another embodiment of the present invention, when PZT (1 or 2mhz, PZT refers to lead zirconate titanate piezoelectric ceramic) having a diameter of 12mm is used, the ultrasonic beam does not spread seriously in the far field region. The average distance of the heart of the fetus from the skin is 90mm. Far-field ultrasound beams have a small cross-sectional area and it is difficult to locate the heart by observing the feedback signal. X is the larger the PZT diameter size becomes N Becomes larger (X) N And a 2 Proportional) much greater than the distance of the skin from the fetal heart. To obtain X N The ultrasonic transceiver probe diameter must be 49mm (1 MHZ) or 35mm (2 MHZ) so that the heart is in the near field region and the diameter size of the ultrasonic beam at the heart location is 49mm or 35mm, although not large enough, nor too small. Thus, the diameter 2a=50 mm of the ultrasonic transceiver probe is the smallest dimension, when the ultrasonic transceiver probe diameter dimension is smaller than 50mm, such as 2a=30 mm, such that the heart distance ratio X N Slightly shorter and the size of the ultrasound beam is much smaller than 30mm, the heart position cannot be located. For more convenient localization of the heart position, an ultrasound beam of large cross-sectional area is required, so the diameter size of the ultrasound transceiver probe must be as large as possible. For example, the ultrasonic transceiver probe diameter 2a=90 mm, the frequency is 2mhz, x N Heart position ratio X of 2.7m N Short, the cross-sectional area of the ultrasonic beam is close to the diameter of the chang' an device by 90mm, and the heart position is easier to point. However, PZT materials are costly and the present embodiment prefers ultrasonic transceiver probes made of piezoelectric polymers.
In one embodiment of the invention, the thickness of the shell is 1/4 wavelength of the sound wave of the shell material; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance. So that a wider bandwidth is designed to provide for a large range of pulse excitation and reception.
In another embodiment of the present invention, in order to be more beneficial to the step-up and the step-down of long pulses with high signal amplitude, a sharp resonant ultrasonic transceiver probe with narrow bandwidth is designed, and the thickness of the shell is N times of half wavelength of the sound wave of the shell material, n=0, 1, 2, 3 or 4; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance.
The ultrasonic transceiver probe of this embodiment has a frequency range of 1MHZ to 2MHZ to avoid negative effects on the fetus. The resonance frequency of the single-layer PVDF and the conductive layer is too high to be suitable for a fetal heart monitor, and the resonance frequency is reduced to 2MHz by designing a multi-layer PVDF ultrasonic transceiver probe in the embodiment, as shown in figure 10, a metal layer is added on the two side surfaces of the polymer layer, and a front matching layer is added to generate bandwidth. The specific structure is as follows: the surfaces of both sides of 52 mu m PVDF60 are symmetrically coated with 12 mu m silver ink 61, after drying, the surfaces of both sides of the silver ink 61 are symmetrically coated with 5 mu m epoxy resin 62, the surfaces of both sides of the epoxy resin 62 are respectively coated with 200 mu m copper 63, and finally, the copper layer 63 near the heart is coated with 300 mu m plastic 64 and mixed grease 65.
In other embodiments of the invention, when PVDF is hollow (or air filled) and has a thickness of up to 500 μm, the front and back metal layers, such as the copper layer described above, can be removed, and when the resonant frequency is 1MHz, the front matching layer can be removed, because the acoustic impedance of the material is close to that of the human body, and the activation pulse is sharp enough to be satisfactory for use, only the substrate PVDF60, the silver ink conductive layer 61, and the thin 25-50 μm polymer protective layer 66 protecting the conductive layers are left as shown in FIG. 11.
According to the embodiment of the invention, the conducting layer on the second surface of the large-area ultrasonic transceiver probe is designed to be separated into the plurality of conducting subareas 2 distributed in the array, the ultrasonic driving device can synchronously drive the plurality of conducting subareas 2 under the driving of the driving voltage, so that the large-area ultrasonic transceiver probe can emit large-cross-section ultrasonic beams to enlarge the coverage area, and accurate positioning is realized; and when receiving the ultrasonic feedback signals, the plurality of conductive subareas 2 independently receive the feedback signals, so that the technical problems of mutual interference of the received feedback signals in different receiving areas of the large-area ultrasonic transceiver probe are solved, and the detection precision is improved.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes using the descriptions and drawings of the present invention or directly or indirectly applied to other related technical fields are included in the scope of the invention.
Claims (9)
1. An ultrasonic transducer array device, comprising: the ultrasonic transceiver probe comprises an ultrasonic driving device and a driving circuit;
the ultrasonic transceiver probe comprises a first conductive layer, a second conductive layer and a substrate, wherein the first conductive layer is attached to a first surface of the substrate, and the second conductive layer is attached to a second surface opposite to the first surface; the second conductive layer comprises a plurality of conductive subareas, and the plurality of conductive subareas are distributed in an insulated manner;
one end of the driving circuit is connected with the ultrasonic driving device, the other end of the driving circuit is connected with each conductive subarea of the ultrasonic transceiver probe, and each conductive subarea respectively receives a driving signal sent by the ultrasonic driving device and generates an ultrasonic signal;
the ultrasonic driving device further comprises a plurality of first anti-parallel diode pairs, wherein the first anti-parallel diode pairs comprise two anti-parallel connected diodes, and the plurality of first anti-parallel diode pairs are respectively connected in series between each conductive subarea and the ultrasonic driving device; the driving signal generated by the ultrasonic driving device under the action of the driving voltage acts on each conductive subarea simultaneously through a plurality of first anti-parallel diode pairs to generate ultrasonic signals and emit the ultrasonic signals, and the ultrasonic feedback signals received by each conductive subarea are respectively prevented from returning to the ultrasonic driving device by the connected first anti-parallel diode pairs
When receiving feedback signals, the switch circuit formed by the first antiparallel diode pair enables each conductive subarea to be an independent feedback signal receiving area.
2. The ultrasonic transducer array device of claim 1, further comprising an ultrasonic feedback signal calculation circuit connected between each of the conductive subregions and each of the first antiparallel diode pairs, receiving the ultrasonic feedback signal received by each of the conductive subregions and calculating the magnitude.
3. The ultrasonic transducer array device according to claim 2, wherein the ultrasonic feedback signal calculation circuit comprises a plurality of signal processing branches, each signal processing branch outputs the ultrasonic feedback signal received by each conductive subarea, and the orientation of the ultrasonic feedback signal with the strongest signal strength is distinguished according to the strength of the ultrasonic feedback signal.
4. An ultrasound transducer array device according to claim 3, wherein the signal processing branch comprises a resistor and a signal amplifier in series; each of the resistors is connected in series between each of the signal amplifiers and each of the conductive subregions.
5. The ultrasonic transducer array device of claim 4, further comprising a plurality of second anti-parallel diode pairs, each of the second anti-parallel diode pairs having one end connected between the resistor and the signal amplifier and the other end grounded.
6. A fetal heart monitor comprising the ultrasonic transducer array device of claim 5.
7. The fetal heart monitor of claim 6 further comprising a housing, wherein the ultrasonic transceiver probe is proximate the inner wall of the housing with the conductive layer of the first surface, and wherein the ultrasonic transceiver probe is planar or arcuately curved.
8. The fetal heart monitor of claim 7 wherein the thickness of the housing is 1/4 wavelength of the acoustic wave of the housing material; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance.
9. The fetal heart monitor of claim 7 wherein the shell has a thickness N times the half wavelength of the shell material sound wave, N = 0, 1, 2, 3 or 4; the acoustic impedance of the housing material is between the ultrasonic transceiver probe material impedance and the propagation medium impedance.
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| CN110328093A (en) * | 2019-04-24 | 2019-10-15 | 深圳爱芯怡科技有限公司 | Ultrasonic atomization equipment and its supersonic atomizer |
| CN111780659B (en) * | 2020-07-02 | 2022-06-28 | 山西工程职业学院 | Touch sensor based on pvdf piezoelectric film |
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