Wearable flexible ultrasonic transducer for breast cyst screening

Abstract

The invention relates to the technical field of flexible ultrasonic transducers, and discloses a wearable flexible ultrasonic transducer for breast cyst screening. The objective of the invention is to solve the problems of low array element density, limited sound wave transmission energy, low imaging effect resolution, no matching layer or shielding of the matching layer, large error caused by analysis of an ultrasonic transducer, inconformity with a KLM model, incapability of realizing high-efficiency ultrasonic capacity transmission, low ultrasonic transducer bandwidth, low resolution, low cost and the like in the prior art. And high-quality imaging is difficult to realize. The flexible wearable ultrasonic transducer is sequentially provided with an electrode substrate, a backing layer, a piezoelectric layer, a first matching layer, a patch and a second matching layer from top to bottom, the acoustic function is enhanced, the flexible ultrasonic transducer which is high in density, free of shielding of the matching layer, high in bandwidth, capable of achieving two-dimensional and three-dimensional multi-dimensional imaging and capable of achieving large-range curvature conformal is developed, and the flexible ultrasonic transducer can be used for long-time continuous screening of breast cysts.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible ultrasonic transducers, and in particular to a wearable flexible ultrasonic transducer for breast cyst screening. Background Art

[0002] Ultrasonic transducers are devices that convert mechanical energy into acoustic energy and are widely used in medical imaging, non-destructive testing and other fields. Traditional ultrasonic transducers are generally made of rigid materials. Although they have high mechanical strength and stable transducer performance, they have certain limitations in some specific applications. In medical imaging, in order to obtain high-quality images, the ultrasonic transducer needs to fit closely to the surface of the human body. Due to the complex curved surface structure on the human body, it is difficult for rigid transducers to achieve good fit, which affects the imaging effect.

[0003] The emergence of flexible ultrasonic transducers provides a new way to solve these problems. Flexible ultrasonic transducers are made of flexible materials, have good mechanical flexibility and deformation adaptability, and can better fit complex curved surfaces and irregular surfaces, thereby significantly improving the application effect. However, there are still many areas for improvement in the design and manufacturing of existing flexible ultrasonic transducers.

[0004] A flexible ultrasonic linear array transducer is disclosed in the Chinese patent document 202210770771.3 in the prior art. The flexible ultrasonic linear array transducer includes a flexible backing layer, a flexible matching layer, and a piezoelectric layer between the flexible backing layer and the flexible matching layer; the piezoelectric layer includes a signal electrode flexible circuit board on the flexible matching layer side, a ground electrode flexible circuit board on the flexible backing layer side, and a plurality of piezoelectric array elements between the signal electrode flexible circuit board and the ground electrode flexible circuit board; gaps filled with flexible isolation materials are arranged between the piezoelectric array elements.

[0005] However, in the implementation of the above scheme, there are at least the following technical problems: most of the existing flexible ultrasonic transducers have low array element density, which limits the energy of sound wave transmission and the imaging effect resolution is low. In addition, there is no matching layer or the matching layer is blocked. This processing method will bring large errors when analyzing the ultrasonic transducer, does not conform to the KLM model, and cannot achieve high-efficiency ultrasonic energy transmission, resulting in low bandwidth and low resolution compared to traditional ultrasonic transducers, making it difficult to achieve high-quality imaging. Therefore, it is urgent to propose a wearable flexible ultrasonic transducer for breast cyst screening. Summary of the invention

[0006] In view of the above technical problems, the present disclosure provides a wearable flexible ultrasonic transducer for breast cyst screening, which solves the technical problems in the prior art that the array element density is low, resulting in limited energy of sound wave transmission, low resolution of imaging effect, and no matching layer or the matching layer is blocked, which will cause large errors when analyzing the ultrasonic transducer, does not conform to the KLM model, and cannot achieve high-efficiency ultrasonic energy transmission, resulting in low bandwidth and resolution of the ultrasonic transducer, and difficulty in achieving high-quality imaging.

[0007] According to one aspect of the present disclosure, a wearable flexible ultrasonic transducer for breast cyst screening is provided, which is sequentially arranged from top to bottom with an electrode substrate, a backing layer, a piezoelectric layer, a first matching layer, a patch, and a second matching layer; the electrode substrate includes a polyimide film to achieve mechanical support, and a copper film is arranged at the bottom of the polyimide film to achieve circuit connection; the backing layer includes a conductive E-solder 3022 two-component silver glue; the piezoelectric layer is a 1-3 composite material cut from a PZT-5H piezoelectric ceramic material, and the piezoelectric layer includes a plurality of array elements, and the array elements include a bottom electrode and an upper electrode; the first matching layer is a conductive matching layer prepared from epoxy resin and silver powder, and the conductive matching layer is connected to the copper film to form a signal electrode; the patch includes three soft probe modules, and the three soft probe modules include a planar array, and two left-right symmetrical linear arrays are connected on both sides of the planar array via hinges; the second matching layer is pure epoxy resin.

[0008] In some embodiments of the present disclosure, the copper film has a thickness of 10 μm.

[0009] In some embodiments of the present disclosure, the backing layer has a thickness of 700 μm to absorb acoustic waves and enhance axial resolution.

[0010] In some embodiments of the present disclosure, the thickness of the piezoelectric layer is 260 μm, the width of the array element is 86 μm, the interval between the slits between adjacent piezoelectric materials is 24 μm, and the volume fraction is 61.12%.

[0011] In some embodiments of the present disclosure, the diameter of the silver powder is 5 μm, and the thickness of the first matching layer is 74 μm.

[0012] In some embodiments of the present disclosure, the second matching layer has a thickness of 127 μm so as to directly contact the skin.

[0013] In some embodiments of the present disclosure, the array spacing between the linear array and the planar array is 0.47 mm, and the linear array and the planar array are interconnected using 8 serpentine hinges with a length of 4 mm, and the serpentine hinges are connected to the backing layer to form a ground electrode.

[0014] In some embodiments of the present disclosure, the linear array includes a flexible linear array consisting of 32 channels.

[0015] In some embodiments of the present disclosure, the array includes 64 channels.

[0016] In some embodiments of the present disclosure, each channel includes 12 array elements connected in series, and the array elements are active elements.

[0017] In some embodiments of the present disclosure, 8 ground lines and 8 array element lines are respectively configured on the upper and lower surfaces of the array element.

[0018] The beneficial effects of the present invention are: 1. The patch design conforms to the various curvatures of the breast for ultrasound imaging and cyst assessment, achieving a high-density, unobstructed matching layer, flexible ultrasound grid array in direct contact with the skin, ensuring efficient transmission of sound waves, and a viscoelastic composite layer that balances the Young's modulus at the probe-skin interface and ensures stable mechanical support for conformal contact with the human body.

[0019] 2. It can be used for long-term continuous screening of breast cysts; high bandwidth realizes wide range curvature conformity for two-dimensional and three-dimensional multi-dimensional imaging; the patch can effectively attenuate the side lobe grating lobe, thereby producing better spatial resolution, and the soft probe can adapt to a larger curvature and volume range to meet the requirements of tight and load-free wear.

[0020] 3. The row and column addressing circuit can realize more channel control methods with very few circuits, and can realize N through 2N electrodes 2 The activation mode greatly simplifies the circuit system of the wearable flexible ultrasonic transducer, and further enhances the lightweight and high flexibility of the wearable device. The design of addressing and activating any array element can realize a customized sound field. The device realizes the "NUAA" letter sound field effect through this method, and is collected by the hydrophone.

[0021] 4. The piezoelectric layer effectively reduces the acoustic impedance, and the effective matching layer can perfectly match the acoustic impedance with the skin's outer interface, effectively improving the efficiency of sound wave transmission so that more sound waves can penetrate into the human skin to improve imaging quality. The backing layer can effectively absorb sound waves to enhance axial resolution.

[0022] 5. The probe ensures that the matching layer has no obstructions on the basis of electrical and mechanical interconnection, so that the ultrasound wave is not affected by obstructions during transmission, more sound waves can be transmitted, and the rigid backing is cut synchronously to improve the backing of the flexible probe. Secondly, the viscoelastic composite layer has an elastic modulus close to that of the skin, which provides a compatible platform for the probe to improve mechanical compliance and durability and reduce crosstalk between array elements. The matching layer of the high-density array elements is directly attached to the skin to promote high-quality imaging. The 3-module soft probe can be used on curved surfaces, providing a large depth and multi-angle imaging field of view, and can achieve two-dimensional and three-dimensional multi-dimensional imaging.

[0023] 6. The present invention has a high bandwidth of -6dB of 81.51% and a low crosstalk of -61.9 dB. The axial and lateral resolutions are 0.38 mm and 0.55 mm respectively, which can be used for comfortable wearing, and has wide-angle and multi-dimensional imaging capabilities, which is helpful for long-term and continuous screening of breast cancer cysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a wearable flexible ultrasonic transducer for breast cyst screening; Figure 2 is a schematic diagram of the bottom electrode structure; Figure 3 Schematic diagram of the upper electrode structure; Figure 4 This is a physical picture of a wearable flexible ultrasonic transducer; Figure 5 This is a partial enlarged view of the wearable flexible ultrasonic transducer; Figure 6 This is an image of a 5 mm fluid cyst; Figure 7 This is the imaging image of a 6 mm solid cyst; Figure 8 This is a comparison of the axial and transverse dimensions of the imaged cyst; Fig. 9 Two 1.5 mm microcalcification mimics and imaging images of cyst boundaries with different elastic moduli; Fig.10 Images of undilated and dilated mammary ducts in the R = 50 / 60 mm phantom group.

[0025] The names of the components in the figure are: 1. Polyimide film; 2. Copper film; 3. Backing layer; 4. 1-3 composite material; 5. First matching layer; 6. Patch; 7. Second matching layer. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. Example 1

[0027] This example discloses a wearable flexible ultrasonic transducer for breast cyst screening, see Figures 1 to 10; From top to bottom, an electrode substrate, a backing layer 3, a piezoelectric layer, a first matching layer 5, a patch 6, and a second matching layer 7 are arranged in sequence; the electrode substrate includes a polyimide film 1 to achieve mechanical support, and a copper film 2 is arranged at the bottom of the polyimide film 1 to achieve circuit connection; the backing layer 3 includes a conductive E-solder 3022 two-component silver paste; the piezoelectric layer is a 1-3 composite material 4 cut from a PZT-5H piezoelectric ceramic material, and the piezoelectric layer includes a plurality of array elements, and the array elements include a bottom electrode and an upper electrode; the first matching layer 5 is a conductive matching layer prepared from epoxy resin and silver powder, and the conductive matching layer is connected to the copper film to form a signal electrode; the patch 6 includes three soft probe modules, and the three soft probe modules include a planar array, and two left-right symmetrical linear arrays are connected on both sides of the planar array by hinges; the second matching layer 7 is pure epoxy resin.

[0028] The copper film 2 has a thickness of 10 μm.

[0029] The backing layer 3 has a thickness of 700 μm to absorb sound waves and enhance axial resolution.

[0030] The thickness of the piezoelectric layer is 260 μm, the width of the array element is 86 μm, the interval between the slits between adjacent piezoelectric materials is 24 μm, and the volume fraction is 61.12%.

[0031] The diameter of the silver powder is 5 μm, and the thickness of the first matching layer is 74 μm.

[0032] The second matching layer 7 has a thickness of 127 μm so as to directly contact the skin.

[0033] The array spacing between the linear array and the planar array is 0.47 mm. The linear array and the planar array are connected to each other using 8 serpentine hinges with a length of 4 mm. The serpentine hinges are connected to the backing layer to form a ground electrode.

[0034] The linear array comprises a flexible linear array consisting of 32 channels.

[0035] The array contains 64 channels.

[0036] Each channel includes 12 array elements connected in series, and the array elements are active components.

[0037] The upper and lower surfaces of the array element are respectively configured with 8 ground lines and 8 array element lines.

[0038] Basic structure: The flexible ultrasonic transducer patch of the present invention is composed of three soft probe modules, which are formed by combining two high-density linear arrays and one planar array. The array spacing is 0.47 mm, and there are 128 channels, which can effectively attenuate the side lobes and grating lobes, thereby producing better spatial resolution. They are connected to each other using 8 serpentine hinges with a length of 4 mm, such as Figure 1 As shown. This soft probe can adapt to a larger curvature and volume range to meet the requirements of tight, load-free wear. The two linear arrays have a symmetrical structure and are composed of 32-channel flexible linear arrays, with each 12 active elements connected in series into one channel.

[0039] Circuit method: The array contains 64 channels, and a row-column addressing circuit is used to realize the two-dimensional array configuration. Eight ground lines and eight element lines are configured on the upper and lower surfaces of the array element respectively. Any corresponding cross-point array element in the 64 array elements can be activated by any row of electrodes and a vertical column of electrodes. Compared with traditional flexible circuit boards, the purpose of the row and column addressing circuit design is to realize more channel control methods through very few circuits, and N2 activation modes can be realized through 2N electrodes, which greatly simplifies the wearable flexible ultrasonic transducer circuit system and further combines the lightweight and high flexibility of wearable devices. The design of addressing and activating any array element can realize a customized sound field. The device realizes the "NUAA" letter sound field effect through this method, and is collected by a hydrophone.

[0040] Preparation of piezoelectric layer: The piezoelectric layer uses PZT-5H material, which is polished to a thickness of 260μm and cut into 1-3 composite materials. The array element width is 86μm, the slit is 24μm, and the volume fraction is as high as 61.12%. This structure effectively reduces the acoustic impedance, but it is still difficult to match the 1.5Mrayl impedance value of the human body. According to the KLM equivalent circuit model, the effective matching layer can perfectly match the acoustic impedance with the outer interface of the skin, effectively improve the efficiency of sound wave transmission, and allow more sound waves to penetrate into the human skin to improve the imaging quality. The flexible ultrasonic transducer patch adopts a double-layer matching layer design. The first layer is matched using epoxy resin and silver powder with a diameter of 5μm to prepare a conductive matching layer with a thickness of 74μm. The second layer is matched to directly contact the skin and is prepared from pure epoxy resin with a thickness of 127μm. The backing layer can effectively absorb sound waves to enhance the axial resolution and is prepared from conductive E-solder 3022 with a thickness of 700μm.

[0041] Electrode preparation and connection: The electrode substrate is composed of a polyimide film and a 10μm copper mold. It is prepared by laser cutting. One part is prepared into a substrate with holes and grooves, and the other part is processed into a serpentine hinge. The copper film realizes the circuit connection and the polyimide layer realizes the mechanical support. When the array element block is cut into small pieces, the matching layer of the piezoelectric block is slightly larger and fixed on the substrate in a "nail shape" through interference fit. The signal electrode is connected by the copper film layer on the substrate and the conductive layer silver-epoxy resin matching layer, while the ground electrode is connected to each other through the serpentine hinge on the backing block. The designed viscoelastic composite layer provides a compatible platform for the probe, which is filled into the array groove after packaging to achieve packaging to improve durability. A layer of Parylene film with a thickness of 5 μm is deposited on the side close to the skin using a coating machine.

[0042] The preparation method of the flexible matrix of the present invention comprises the following steps: processing the signal electrode and the ground electrode of the flexible ultrasonic transducer by a laser direct engraving system (ProtoLaser U3, LPKF); micro-cutting the piezoelectric block by a dicing machine (DAD323, DISCO Corporation); and bonding and curing the upper and lower electrode layers of the flexible ultrasonic patch.

[0043] The flexible ultrasonic transducer array works as follows: Module 1 row-column addressable flexible stretchable ultrasonic transducer array working mode: The bottom electrode of each row of piezoelectric array elements is electrically connected to the row array, and the top electrode of each column of piezoelectric array elements is electrically connected to the column array; By stimulating a row wiring pad and a column wiring pad, the piezoelectric array elements corresponding to the row and column wiring pads can be stimulated to work; By stimulating a row pad and all column pads, all piezoelectric array elements in the row can be stimulated to work; By stimulating all row pads and column pads, all piezoelectric array elements can be stimulated to make them work.

[0044] The working mode of the linear array ultrasonic transducer array of module 2 and module 3 is as follows: Each column of piezoelectric array elements is arranged in a straight line, and the transducer unit realizes the working state through group control; By stimulating a wiring disk, a row of piezoelectric array elements corresponding to the wiring disk can be stimulated to make it work; By stimulating multiple wiring pads, multiple columns of piezoelectric array elements corresponding to these wiring pads can be stimulated to make them work; By stimulating all the pads, all the piezoelectric array elements can be stimulated to make them work.

[0045] Although some preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0046] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of this application and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A wearable flexible ultrasonic transducer for breast cyst screening, characterized in that: An electrode substrate, a backing layer, a piezoelectric layer, a first matching layer, a patch, and a second matching layer are sequentially arranged from top to bottom; the electrode substrate comprises a polyimide film to provide mechanical support, and a copper film is arranged at the bottom of the polyimide film to achieve circuit connection; the backing layer comprises a conductive E-solder 3022 two-component silver paste; the piezoelectric layer is a 1-3 composite material cut from a PZT-5H piezoelectric ceramic material, and the piezoelectric layer comprises a plurality of array elements, and the array elements comprise a bottom electrode and an upper electrode; the first matching layer is a conductive matching layer prepared from epoxy resin and silver powder, and the conductive matching layer is connected to the copper film to form a signal electrode; the patch comprises three soft probe modules, and the three soft probe modules comprise a planar array, and two left-right symmetrical linear arrays are connected on both sides of the planar array via hinges; the second matching layer is pure epoxy resin.

2. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The copper film has a thickness of 10 μm.

3. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The backing layer has a thickness of 700 μm to absorb acoustic waves and enhance axial resolution.

4. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The thickness of the piezoelectric layer is 260 μm, the width of the array element is 86 μm, the interval between the slits between adjacent piezoelectric materials is 24 μm, and the volume fraction is 61.12%.

5. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The diameter of the silver powder is 5 μm, and the thickness of the first matching layer is 74 μm.

6. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The second matching layer has a thickness of 127 μm to directly contact the skin.

7. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The array spacing between the linear array and the planar array is 0.47 mm. The linear array and the planar array are connected to each other using 8 serpentine hinges with a length of 4 mm. The serpentine hinges are connected to the backing layer to form a ground electrode.

8. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The linear array comprises a flexible linear array consisting of 32 channels.

9. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: The area array comprises a flexible linear array consisting of 64 channels.

10. The wearable flexible ultrasonic transducer for breast cyst screening according to claim 1, characterized in that: Each channel includes 12 array elements connected in series, and the array elements are active elements; 8 ground lines and 8 array element lines are respectively arranged on the upper and lower surfaces of the array elements.

Images