CN118253475A - Impedance anti-matching backing-based small interventional ultrasonic catheter transducer - Google Patents

Abstract

The application discloses a small interventional ultrasonic catheter transducer design based on an impedance anti-matching backing. The small interventional ultrasonic catheter transducer comprises a packaging layer, an FPC circuit, a second anti-matching layer, a first anti-matching layer, a piezoelectric layer, a first matching layer, a second matching layer and an acoustic lens layer which are sequentially arranged from bottom to top. The total thickness of the second and first anti-matching layers is close to the thickness of the piezoelectric layer, and the extremely high reflectivity thereof allows almost no acoustic energy to be transmitted into the backing layer, so that the traditional thick backing structure can be eliminated, and the size of the transducer can be greatly reduced. The reduction in transducer size provides a large amount of available space for the placement of FPC circuitry so that the small interventional ultrasound catheter transducer may have a more space-efficient design. The proposed impedance-back-matching based catheter transducer design provides a viable solution for miniaturization of interventional ultrasound catheter transducers.

Description

Impedance anti-matching backing-based small interventional ultrasonic catheter transducer

Technical Field

The invention relates to the technical field of medical ultrasonic detection instruments, in particular to a small interventional ultrasonic transducer and a design and manufacturing method of the ultrasonic transducer.

Background

With the increasing popularity of minimally invasive interventional procedures, the application of ultrasound image guidance techniques in this field is particularly critical. However, existing ultrasound imaging techniques face a number of challenges. Body surface ultrasound is limited by the narrow acoustic window, insufficient deep resolution, and significant impact of factors such as obesity, gases and bones on imaging quality. Although the intracavitary ultrasound, such as intracardiac ultrasound and cardiovascular ultrasound, can directly observe the intracavitary structure, the field of view is still significantly insufficient. Rigid laparoscopic ultrasound is not flexible to operate and causes major trauma due to the rigid tube design. Therefore, developing a small interventional ultrasound catheter transducer that can accurately provide high-resolution imaging guidance in real time is of great significance in promoting progress in minimally invasive interventional procedures.

However, the design of small interventional ultrasound catheter transducers presents a significant challenge in terms of how to optimize the transducer structure in a very small space to compromise imaging quality and catheter size. Conventional ultrasound transducer structures include an acoustic matching layer, a piezoelectric layer, and a backing layer. The piezoelectric layer is used as a core component and is responsible for transmitting and receiving ultrasonic waves. The acoustic matching layer is used for solving the problem of acoustic impedance mismatch between the piezoelectric layer and human tissues so as to improve the transmission efficiency of sound waves. However, the backing layer occupies more than 80% of the thickness in conventional constructions, in order to eliminate acoustic waves entering the backing layer and avoid creating image artifacts. This design, while guaranteeing the imaging quality, severely restricts the miniaturization of the transducer.

In order to achieve miniaturization of the transducer without sacrificing imaging quality, the conventional structure must be optimized. Accordingly, this patent proposes a small interventional ultrasound catheter transducer based on impedance reverse-matching backing technology. The technology effectively reduces the thickness of the backing layer through a carefully designed backing structure, and simultaneously maintains the functions of eliminating sound waves and preventing image artifacts. The method can not only greatly reduce the overall size of the transducer and make the transducer more suitable for interventional catheters, but also maintain or even improve imaging quality, thereby providing powerful support for accurate minimally invasive surgery.

Disclosure of Invention

The invention aims to solve the problem that the ultrasonic catheter transducer in the prior art is difficult to realize miniaturization while maintaining imaging quality, and provides a small interventional ultrasonic catheter transducer based on an impedance anti-matching backing. The thickness of the transducer can be controlled to be 1-2mm, the width can be controlled to be within 3mm, and the transducer can conveniently pass through a tissue gap through an interventional approach and approach an operation area, so that high-resolution real-time imaging guidance is realized.

In order to achieve the above object, the present invention provides the following solutions:

The invention provides a small interventional ultrasonic catheter transducer based on an impedance anti-matching backing, which comprises an FPC circuit, a second anti-matching layer, a first anti-matching layer, a piezoelectric layer, a first matching layer, a second matching layer, an acoustic lens layer and an external packaging layer from bottom to top.

The FPC circuit is flexibly designed and used for connecting electrodes of each array of the piezoelectric layer, can be bent inside the transducer to adapt to the shape of a catheter, and is reliably connected with an external connector, the total thickness of the FPC circuit is controlled to be hundred micrometers, and the compactness of the overall size of the transducer is ensured; the FPC circuitry and bottom packaging layer constitute an equivalent backing layer for the transducer.

The anti-matching layer aims at increasing the reflection coefficient between the piezoelectric layer and the equivalent backing layer, so that the ultrasonic energy entering the equivalent backing layer is effectively reduced; the anti-matching layer is designed with two different principle implementation modes, one is an anti-matching structure based on equivalent ultralow acoustic impedance, and the anti-matching structure comprises a double-layer structure and a single-layer structure; the other is an anti-matching structure based on equivalent ultrahigh acoustic impedance, and is usually a single-layer structure; this design significantly reduces the thickness of the backing layer while ensuring imaging quality, thereby enabling miniaturization of the transducer.

The piezoelectric layer is used as a core component and is used for receiving the voltage excitation signal and generating forward ultrasonic waves and backward ultrasonic waves; the forward ultrasonic wave is an ultrasonic wave transmitted by the piezoelectric layer to the matching layer; the backward ultrasonic wave is an ultrasonic wave transmitted from the piezoelectric layer to the anti-matching layer; the piezoelectric layer may also be used to receive ultrasonic waves and generate electrical signals.

The first matching layer and the second matching layer are used for solving the problem of unmatched interface acoustic impedance of ultrasonic waves between human tissues and the piezoelectric layer, and the ultrasonic wave transmission efficiency is improved by optimizing the material and the thickness of the matching layer, so that the bandwidth of the transducer is improved, and the imaging definition is ensured.

The acoustic lens layer is used for focusing the acoustic beam of the catheter transducer in the elevation direction so as to enhance the sensitivity of the transducer and further improve the image quality.

The packaging layer plays a role in protecting the sound head and the internal structure thereof, has good insulating property, and ensures the safety and the service life of the transducer.

Optionally, in the double-layer anti-matching structure based on the equivalent ultralow acoustic impedance, the thicknesses of the first anti-matching layer and the second anti-matching layer are generally 0.1-0.4 times of the wavelength of the ultrasonic wave, and preferably 0.25 times of the wavelength thickness is selected; the ultrasonic wave wavelength is the ultrasonic wave wavelength when the ultrasonic wave is transmitted to the functional layer.

Optionally, the anti-matching based on the equivalent ultralow acoustic impedance can be of a single-layer structure or a double-layer structure, if the anti-matching based on the equivalent ultralow acoustic impedance is of a single-layer structure, a first anti-matching layer is made of a low acoustic impedance material, epoxy resin, polyvinyl chloride, polypropylene and the like can be selected, the thickness of a second anti-matching layer is zero, and the backing is required to be made of a high acoustic impedance material with larger thickness; if the structure is a double-layer structure, the first anti-matching layer is made of low acoustic impedance materials, the second anti-matching layer is made of high acoustic impedance materials, and simple substance metals, steel, tungsten steel and the like can be selected without a backing layer.

Optionally, the anti-matching based on the equivalent ultrahigh acoustic impedance is generally of a single-layer structure, the anti-matching layer is made of high acoustic impedance materials, simple substance metals, steel, tungsten steel and the like can be selected, and the thickness is generally 0.1-0.3 times of the wavelength of ultrasonic waves in the materials; the anti-matching structure based on equivalent ultra-high acoustic impedance requires a piezoelectric layer thickness of 0.25 times the ultrasonic wavelength to satisfy the "fixed-free" resonance relationship of the piezoelectric layer.

Optionally, the piezoelectric layer material includes, but is not limited to, piezoelectric ceramics, piezoelectric single crystals, and/or piezoelectric composites, etc.

Alternatively, the matching layer is typically 0.15-0.35 times the ultrasound wavelength per layer thickness.

Optionally, the acoustic lens material includes, but is not limited to, low acoustic velocity rubber material, high acoustic velocity polystyrene, and the like.

Alternatively, the shape and type of the ultrasound transducer with power output and imaging capabilities includes, but is not limited to Shan Zhenyuan planar, shan Zhenyuan focused, planar array, and curved array.

The invention has the beneficial effects that: the invention designs a small interventional ultrasonic catheter transducer based on an impedance anti-matching backing, which greatly hinders the penetrating efficiency of ultrasonic energy at the backing, so that a thick backing layer is not needed to attenuate backward ultrasonic waves, thereby eliminating the traditional thick backing structure and greatly reducing the size of the transducer; meanwhile, the bandwidth of the catheter transducer is improved through the parameter optimization of the matching layer, and the imaging quality of the catheter transducer is slightly reduced compared with that of the traditional ultrasonic transducer; the backing structure based on impedance anti-matching is not only suitable for small interventional ultrasonic catheter transducers, but also suitable for other application scenes with limitation on the size of the probe.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a basic block diagram of an ultrasound catheter transducer based on an impedance reverse-matching backing provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a product provided by an embodiment of the present invention;

Symbol description: 1-FPC circuit, 2-second anti-matching layer, 3-first anti-matching layer, 4-piezoelectricity layer, 5-first matching layer, 6-second matching layer, 7-sound lens layer, 8-encapsulation layer, 9-electrode welding point, 10-handle, 11-steering wheel, 12-sheath pipe, 13-catheter transducer.

Detailed Description

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is apparent that the specific embodiments described herein are only for explaining the present invention and are not limiting the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention aims to provide a small interventional ultrasonic catheter transducer based on an impedance anti-matching backing, which greatly reduces the penetrating efficiency of backward ultrasonic energy by adopting an impedance anti-matching backing structure, so that a thick backing layer is not required to be adopted to eliminate backward ultrasonic waves. The design not only reduces the overall size of the transducer, but also provides a certain support and sensitivity improvement for the piezoelectric layer through the impedance anti-matching backing structure, thereby enhancing the imaging depth and contrast of the ultrasonic catheter transducer.

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Fig. 1 is a basic block diagram of a small interventional ultrasound catheter transducer based on an impedance anti-matching backing provided by an embodiment of the present invention. As shown in fig. 1, the ultrasonic transducer in this embodiment includes an FPC circuit 1, a second anti-matching layer 2, a first anti-matching layer 3, a piezoelectric layer 4, a first matching layer 5, a second matching layer 6, an acoustic lens layer 7, an external package layer 8, and an array electrode pad 9, which are sequentially disposed from bottom to top.

The FPC circuit 1 is used for connecting each array of transducers with each channel of a host receiver, has the functions of electric signal excitation and pulse echo signal reception, and has the characteristics of small size and flexibility.

The second anti-matching layer 2 is typically made of a high acoustic impedance material, in this embodiment a tungsten steel material, with an acoustic impedance of about 97MRayl and a thickness of 0.24 lambda.

The first anti-matching layer 3 is typically made of a low acoustic impedance material, so that its equivalent acoustic impedance to the second anti-matching layer 2 becomes extremely low, and in this embodiment an epoxy resin is selected, with an acoustic impedance of 2.7MRayl and a thickness of 0.24 lambda.

The piezoelectric layer 4 is made of PZT-5H ceramic material in the embodiment to meet the high bandwidth requirement, and has two microelements in an array with acoustic impedance of about 20MRayl.

The first matching layer 5 and the second matching layer 6 are used for increasing transmission of sound waves between the piezoelectric layer 4 and the medium, and improving bandwidth and transmission efficiency of the ultrasonic transducer, in this embodiment, the first matching layer 5 is made of a mixture material of tungsten powder and epoxy resin, acoustic impedance is 8.5MRayl, the second matching layer 6 is made of epoxy resin, acoustic impedance is 2.7MRayl, and thickness is 0.24 lambda.

The acoustic lens layer 7 is used for focusing the sound field of the catheter transducer, so that the energy is more concentrated, the ultrasonic imaging quality is improved, and meanwhile, the insulation and protection effects are also achieved.

The outer encapsulation layer 8 serves to protect the catheter transducer and provides some strength support for the transducer.

The electrode welding points 9 are used for connecting each vibration element of the transducer with each welding point of the FPC circuit 1, so that electric contact is ensured with higher stability.

Fig. 2 is a schematic diagram of a product according to an embodiment of the present invention. As shown in fig. 2, the product in this embodiment includes a handle 10, steering wheel 11, sheath 12 and catheter transducer 13.

The handle 10 provides an operable platform for the operator and integrates a steering wheel 11 and a sheath 12.

The steering wheel 11 is used for controlling the change of the shape and the orientation of the catheter, and is controlled in a mechanical transmission manner in the embodiment, and the main control manners are rotation of a rotating part, stirring of a steering rod, bending of a deformable part and the like.

The sheath 12 is used to provide access to the catheter during surgical or interventional imaging procedures and includes a main body section, an adjustable bend section, and a distal bend.

The catheter transducer 13 is used for uniform and high-resolution ultrasound imaging of a focal site in a human body, and has a small-sized characteristic.

The small interventional ultrasonic catheter transducer based on impedance anti-matching has the characteristic of small size, an impedance anti-matching backing structure is used, the size of a sound head is about 1mm, the diameter of the transducer is within 3mm, and the small size requirement of the interventional catheter transducer is met.

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims (7)

1. The small interventional ultrasonic catheter transducer based on the impedance anti-matching backing is characterized by comprising a packaging layer, an FPC circuit, a second anti-matching layer, a first anti-matching layer, a piezoelectric layer, a first matching layer, a second matching layer and an acoustic lens layer which are sequentially arranged from bottom to top.

The packaging layer is used for insulation and protection, the width of the packaging layer is less than or equal to 3mm, and the total thickness of the packaging layer is less than or equal to 2mm; the FPC circuit is used for connecting each array of the transducer with each channel of the host receiver; the second and first anti-matching layers are used for eliminating a traditional thick backing layer, reducing the size of the interventional ultrasonic catheter transducer, and preventing echo artifacts caused by insufficient backing thickness in the design of the transducer from seriously affecting imaging quality; the piezoelectric layer is used for receiving the electric signal excitation so as to generate ultrasonic waves, and receiving the ultrasonic waves so as to generate electric signals; the first matching layer and the second matching layer are used for increasing the transmission degree of ultrasonic waves, improving the sensitivity of the transducer, improving the waveform of the ultrasonic waves and increasing the bandwidth of the ultrasonic transducer; the acoustic lens layer is used for insulation and protection, and is also used for focusing the sound field of the elevation direction of the transducer, so that adverse effects caused by a large diffusion angle are reduced.

2. The impedance reverse-matching backing-based miniature interventional ultrasound catheter transducer of claim 1, wherein the encapsulation layer is made of flexible materials such as rubber and plastic, and the shape thereof includes but is not limited to cylindrical, square, ellipsoidal, etc.

3. The impedance reverse-matching backing-based miniature interventional ultrasound catheter transducer of claim 1, wherein FPC circuit thickness is generally less than 100 μιη; the line spacing is determined according to specific frequency and is generally less than or equal to 0.3mm; the length is equal to the number of arrays multiplied by the line spacing; the width is the width of the FPC, and the width can be reduced to be within 3mm in many cases through folding.

4. The impedance-back-matching-based miniature interventional ultrasound catheter transducer of claim 1, wherein the second anti-matching layer is made of a high acoustic impedance material, the acoustic impedance of which is generally higher than that of the piezoelectric layer material, and preferably a high acoustic impedance metal material is selected, and the thickness is between 0.1 and 0.3λ; the first anti-matching layer is made of low acoustic impedance materials, the acoustic impedance of the first anti-matching layer is generally lower than 7MRayl, and the first anti-matching layer is made of low acoustic impedance epoxy resin, organic materials and the like, and the thickness of the first anti-matching layer is between 0.1 and 0.3λ; the ratio of the acoustic impedance of the second anti-matching layer to that of the first anti-matching layer is greater than or equal to 10, and the larger the ratio is, the better the anti-matching effect is.

5. The impedance reverse-matching backing-based miniature interventional ultrasound catheter transducer of claim 1, wherein the array of piezoelectric layers comprises a total of 8-512 array elements, each array element being controllable for ultrasound transmission and reception; the-6 dB center frequency of the ultrasonic transducer is within 4-40 MHz; selecting a piezoelectric layer material having broadband characteristics;

The center frequency refers to the average value of the upper and lower limits of the frequency corresponding to the-6 dB frequency spectrum of each working frequency band;

the broadband piezoelectric layer material includes but is not limited to piezoelectric ceramics, piezoelectric single crystals, piezoelectric polymers, piezoelectric composites and the like.

6. The impedance-back-matching based miniature interventional ultrasound catheter transducer according to claim 1, wherein the selection of the first and second matching layer materials includes, but is not limited to, ceramic materials, metallic materials, inorganic materials, organic materials, and hybrid materials, etc., and the matching layer structure treasury is not limited to a single layer structure composed of a single material, a multi-layer structure composed of a plurality of different materials, a phonon crystal structure, a metamaterial structure, a bio-matching structure, etc.

7. The impedance-back-matching based miniature interventional ultrasound catheter transducer according to claim 1, wherein the acoustic lens material includes but is not limited to rubber and epoxy materials and the like, and the shape thereof includes but is not limited to spherical, ellipsoidal, parabolic, hyperbolic and the like.