Wearable ultrasonic transducer of bionic dionaea muscipula and preparation method of wearable ultrasonic transducer

Abstract

The invention provides a wearable ultrasonic transducer of bionic dionaea muscipula and a preparation method, the wearable ultrasonic transducer comprises a flexible circuit board and two linear arrays which are located on the flexible circuit board and have the same structure and size, and the bionic dionaea muscipula is designed by utilizing the mechanical structure of the bionic dionaea muscipula. In other words, the two linear arrays can be bent inwards to get close to each other like the dionaea muscipula blades when the flexible circuit board is bent, simultaneous imaging of double sections is achieved, a wider imaging view field and higher resolution are provided, and the flexible circuit board can adapt to large curvature changes of the skin part attached to the flexible circuit board without extrusion.

Description

Technical Field

[0001] The present invention relates to the technical field of wearable ultrasonic transducers, and particularly to a wearable ultrasonic transducer for guiding puncture. Background Art

[0002] As a mechanical wave with zero radiation, ultrasonic waves are widely used in important fields such as medical diagnosis, health detection, and intraoperative ultrasound because they can penetrate into human tissues and organs non-invasively and without radioactivity, helping doctors better diagnose, analyze, and treat diseases. However, most traditional ultrasonic transducers have disadvantages such as large volume and inconvenient carrying, and patients usually need to maintain a fixed posture during diagnosis. In addition, the contact interface between the rigid probe and the skin cannot be well coupled, and wearable imaging cannot be achieved. In recent years, due to the development of miniaturization and flexible electronics, wearable ultrasonic devices have developed rapidly.

[0003] Compared with traditional probes, wearable ultrasonic devices have unique advantages such as long-term usability and operator independence, and their independence has been proven in continuous monitoring, non-invasive treatment, etc. In addition, wearable ultrasound also shows its unique advantages in the ablation treatment of liver tumors and prostate biopsy. Ultrasonic transducers play a crucial role in the diagnosis and treatment of thyroid diseases.

[0004] Thyroid nodules are one of the common thyroid diseases, and ultrasonic imaging technology plays an important role in the preoperative detection and intraoperative biopsy of thyroid nodules. However, the traditional rigid hand-held ultrasonic probes currently used in clinical practice have problems such as large volume, complex operation, limited imaging field of view, etc., and require a high level of operation skills for doctors. Secondly, when the existing flexible ultrasonic transducers change with the skin curvature, the change in the element spacing will lead to a decrease in resolution, and their spatial position and angle are difficult to predict, restricting their application in clinical practice. And for flexible stretchable transducers, as the element spacing becomes larger, the resolution and imaging quality of the transducer will be greatly reduced. Therefore, there is an urgent need to propose a wearable ultrasonic transducer for thyroid ultrasound detection and guiding thyroid nodule puncture. Summary of the Invention

[0005] The purpose of the present invention is to provide a wearable ultrasonic transducer imitating a Venus flytrap, which can fit on the skin surface and has high resolution, a wide imaging field of view, and good skin curvature adaptability.

[0006] The present invention also provides a preparation method and application of the wearable ultrasonic transducer imitating a Venus flytrap.

[0007] To achieve the above technical purpose, the wearable ultrasonic transducer imitating a Venus flytrap of the present invention adopts the following technical solutions:

[0008] A wearable ultrasonic transducer imitating a Venus flytrap, comprising a flexible circuit board and two linear arrays with the same structure and size located on the flexible circuit board;

[0009] The linear array is a 64-element linear array with an element pitch of 220 μm; the linear array includes a signal electrode, a piezoelectric composite layer, a ground electrode and a matching layer stacked from bottom to top; the flexible circuit board is provided with leads that are electrically connected to the signal electrode in a matching manner;

[0010] There is a gap between the two linear arrays, and when the flexible circuit board is bent, the upper surfaces of the two linear arrays approach each other and the planes where the upper surfaces of the two linear arrays are located form an angle.

[0011] Furthermore, the piezoelectric composite layer is a 1-3 piezoelectric composite, and the 1-3 piezoelectric composite is a ceramic material, which has a number of parallel slits and forms a number of parallel piezoelectric ceramic strips between two adjacent slits. Each piezoelectric ceramic strip has a width of 90 μm, and each slit has a width of 20 μm.

[0012] Furthermore, the matching layer is divided into two layers, including a first matching layer covering the ground electrode and a second matching layer covering the first matching layer; the first matching layer is a mixture of epoxy resin and alumina powder, and the weight ratio of epoxy resin to alumina powder is 1:1.2; the second matching layer is pure epoxy resin.

[0013] Furthermore, a flexible back lining layer is also provided on the back of the flexible circuit board. The flexible back lining layer is a mixture of composite soft glue, tungsten powder, hollow glass powder and silica, and the weight ratio of composite soft glue, tungsten powder, hollow glass powder and silica is 1:1:0.3:0.05; the composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:6.

[0014] Furthermore, the gap width between the two linear arrays is 4 mm; the thickness of the piezoelectric composite layer is 260 μm, the thickness of the first matching layer is 140 μm, and the thickness of the second matching layer is 110 μm; the thickness of the signal electrode is 20 μm, and the thickness of the ground electrode is 20 μm.

[0015] Furthermore, the slits are filled with epoxy resin.

[0016] Furthermore, the two linear arrays are used to perform ultrasonic imaging on two sections simultaneously.

[0017] The present invention also provides a technical solution for a preparation method of the above-mentioned wearable ultrasonic transducer imitating a Venus flytrap, including:

[0018] Preparation of piezoelectric composite layer: The piezoelectric composite is cut with a cutting spacing of 110 μm and a slit width of 20 μm. The slit is filled with epoxy resin and cured at room temperature. Subsequently, the piezoelectric composite is ground to a thickness of 260 μm. On one side of the piezoelectric material, a 50-nm Cr layer is sputtered first, and then a 200-nm Au layer is sputtered. Then, on the other side of the piezoelectric material, a 50-nm Cr layer is sputtered first, and then a 200-nm Au layer is sputtered.

[0019] Preparation of the matching layer: The matching layer is divided into two layers. The first matching layer is a mixture of epoxy resin and alumina powder, and the weight ratio of epoxy resin to alumina powder is 1:1.2. The mixture is centrifuged at a centrifugal speed of 3000 r / min for 15 minutes, and then post-cured and polished to a thickness of 140 μm. The second matching layer is pure epoxy resin, which is polished to a thickness of 110 μm. The second matching layer is covered on the first matching layer.

[0020] Furthermore, a flexible backing layer is also provided on the back of the flexible circuit board. The flexible backing layer is a mixture of composite soft glue, tungsten powder, hollow glass powder, and silica, and the weight ratio of composite soft glue, tungsten powder, hollow glass powder, and silica is 1:1:0.3:0.05. The composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:6.

[0021] The flexible backing layer is poured on the back of the flexible circuit board, and the thickness of the flexible backing layer is 3 mm.

[0022] Compared with the prior art, the present invention has the following beneficial effects: By using the mechanical structure design of the bionic Venus flytrap, that is, two linear arrays can bend inward and approach each other like the leaves of a Venus flytrap when the flexible circuit board bends, realizing dual-section simultaneous imaging, providing a wider imaging field of view and higher resolution, and being able to adapt to large curvature changes of the skin part to which it is attached without being squeezed.

[0023] Furthermore, the flexible backing block is poured on the flexible circuit board, which can be used to absorb the sound waves transmitted in the reverse direction by the piezoelectric block, thereby improving the bandwidth and providing good mechanical support for the transducer.

[0024] The present invention also provides an application of the above-mentioned wearable ultrasonic transducer of the bionic Venus flytrap in ultrasonic imaging during thyroid nodule puncture biopsy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the wearable ultrasonic transducer of the bionic Venus flytrap of the present invention, and three states are shown;

[0026] Figure 2 It is an exploded schematic structural diagram of the wearable ultrasonic transducer of the present invention;

[0027] Figure 3 It is a real photo of the arrangement of signal electrodes on the flexible circuit board;

[0028] Figure 4 It is a microscopic real photo of the cross-section of the piezoelectric composite material;

[0029] Figure 5 It is a test chart for the self-made phantom imaging test of the wearable ultrasonic transducer of the present invention;

[0030] Figure 6 It is a test chart for the human thyroid imaging test of the wearable ultrasonic transducer of the present invention;

[0031] Figure 7 It is a flowchart of the preparation method of the wearable ultrasonic transducer of the present invention. Detailed implementation manners

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0033] Example 1

[0034] Please refer to Figure 1 As shown, a wearable ultrasonic transducer of a bionic Venus flytrap provided by the present invention includes a flexible circuit board 1 and two linear arrays 2 with the same structure and size located on the flexible circuit board. A flexible back lining layer 3 is provided on the back of the flexible circuit board 1. The design inspiration of the present invention comes from the mechanical structure of the Venus flytrap. Two symmetrically arranged linear arrays are used to perform ultrasonic imaging on two sections simultaneously, which can provide a wider imaging field of view and higher resolution; the design of the flexible circuit board and the flexible back lining layer enables the transducer to have good flexibility and wearability.

[0035] Please combine Figure 2 As shown, it is a schematic exploded view of the structure of the wearable ultrasonic transducer. The linear array is a 64-element linear array, and the element pitch is 220 μm. The linear array includes a signal electrode 4, a piezoelectric composite layer 5, a ground electrode 6, a first matching layer 7 covering the ground electrode 6, and a second matching layer 8 covering the first matching layer 7 stacked from bottom to top. The flexible circuit board 1 is provided with leads that are electrically connected to the signal electrodes in a matching manner. As Figure 3 As shown, since the element pitch is 220 μm, the pitch of the signal electrodes 4 that are electrically connected to the elements one by one is also 220 μm.

[0036] As Figure 1As shown, there is a gap between the two linear arrays, which is set to 4 mm in this embodiment. The thickness of the piezoelectric composite layer is 260 μm, the thickness of the first matching layer is 140 μm, and the thickness of the second matching layer is 110 μm; the thickness of the signal electrode is 20 μm, and the thickness of the ground electrode is 20 μm. When the flexible circuit board 1 is bent, the upper surfaces of the two linear arrays approach each other and the planes where the upper surfaces of the two linear arrays are located form an angle. Figure 1 It includes three states, namely the "planar phased array" state when the flexible circuit board 1 is not bent, the state when the flexible circuit board 1 is bent by 45°, and the state when it is bent by 90°. When the wearable ultrasonic transducer is placed on the skin, the flexible circuit board 1 will be bent based on the large curvature change of the skin, enabling the two linear arrays to fit well on the skin surface. The minimum bending radius of the flexible circuit board in this embodiment is 10.5 mm.

[0037] In this embodiment, the piezoelectric composite layer is a 1-3 piezoelectric composite, and the specific model is PZT-5H(3203HD) piezoelectric ceramic. Please combine Figure 4 As shown, it is a microscopic real photo of the cross-section of the piezoelectric composite. There are several parallel slits in the 1-3 piezoelectric composite, and several parallel piezoelectric ceramic strips are formed between two adjacent slits. The width of each cut piezoelectric ceramic strip is 90 μm, and the width of each slit is 20 μm, that is, the cutting spacing is 110 μm; each transducer element contains two ceramic strips and two slits, that is, the element spacing is 220 μm.

[0038] The first matching layer 7 is a mixture of epoxy resin and alumina powder (particle size 2-3 μm), and the weight ratio of epoxy resin to alumina powder is 1:1.2; the second matching layer 8 is pure epoxy resin, and the specific model is EPO-TEK 301 epoxy resin. The flexible backing layer 3 is a mixture of composite soft glue, tungsten powder, hollow glass powder, and silica, and the weight ratio of composite soft glue, tungsten powder, hollow glass powder, and silica is 1:1:0.3:0.05; the composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:6.

[0039] Perform electrical and acoustic performance tests on the wearable ultrasonic transducer in this embodiment, including:

[0040] Impedance analysis: Use an impedance analyzer (E4990A, Keysight Technologies, Santa Rosa, CA, USA) to measure the resonant frequency and anti-resonant frequency of each element, and calculate the electromechanical coupling coefficient k t :

[0041]

[0042] where f r and f a are the resonance frequency and anti-resonance frequency, respectively.

[0043] The measured resonance frequency is 6.1 MHz, the anti-resonance frequency is 7.6 MHz; the electromechanical coupling coefficient is 0.63.

[0044] Pulse echo response test: Use an ultrasonic pulse transceiver (DPR500, JSR Ultrasonics, Pittsburgh, NY, USA) to measure the pulse echo response of the transducer and calculate the center frequency and bandwidth. After testing, the center frequency of this wearable ultrasonic transducer is 6 MHz, the sensitivity is 402.15 mV, and the -6 dB bandwidth is 74.5%.

[0045] Crosstalk test: Use a signal generator (Tektronix AFG3252C, Tektronix Tech., Beaverton, OR, USA) to excite a certain element of the transducer and measure the crosstalk level of adjacent elements. The lowest crosstalk of this transducer is measured to be -49.5 dB, which is lower than the international standard of -30 dB for element crosstalk, indicating that the interference between the transducer elements is relatively low and meets the design expectations.

[0046] Perform imaging performance tests on the wearable ultrasonic transducer in this embodiment, including:

[0047] Commercial phantom imaging: Use a commercial phantom (KS107BG(N-3), Institute of Acoustics, Chinese Academy of Sciences, China) to test the axial and lateral resolutions. The measured axial resolution of this transducer is 0.62 mm, and the lateral resolution is 0.68 mm, which meets the design expectations.

[0048] Self-made phantom imaging: As Figure 5 shown, use a self-made agar-based anechoic cyst phantom for imaging tests to simulate cystic and calcified nodules of thyroid nodules. Simulate a percutaneous biopsy operation through a puncture needle to verify the clinical application ability of the transducer. Figure 5 The clear position of the puncture needle in the phantom can be seen in

[0049] Human thyroid imaging: As Figure 6 shown, image the thyroid of a healthy adult male to verify the imaging effect of the transducer in actual clinical applications. Figure 6 The clear and complete images of the thyroid in two sections can be seen in

[0050] Example 2

[0051] This embodiment is a preparation method of the wearable ultrasonic transducer of the bionic Venus flytrap in Embodiment 1.

[0052] Please refer to Figure 7 as shown, the preparation method includes:

[0053] Preparation of the piezoelectric composite layer: Cut the piezoelectric composite material (PZT-5H (3203HD) piezoelectric ceramic) with a cutting spacing of 110 μm and a slit width of 20 μm; fill the slit with epoxy resin (epoxy resin model: Epo-Tek 301) and cure it at room temperature. Subsequently, grind the piezoelectric composite material to a thickness of 260 μm and a width of 0.09 mm (thickness-width ratio is 2.89, volume fraction is 66.9%). First, sputter a 50-nm Cr layer on one side of the piezoelectric material, then sputter a 200-nm Au layer; then on the other side of the piezoelectric material, first sputter a 50-nm Cr layer and then sputter a 200-nm Au layer.

[0054] Preparation of the matching layer: Divide the matching layer into two layers. The first matching layer is a mixture of epoxy resin and alumina powder, and the weight ratio of epoxy resin to alumina powder is 1:1.2; centrifuge this mixture at a centrifugal speed of 3000 r / min for 15 minutes, then post-cure and polish it to a thickness of 140 μm; the second matching layer is pure epoxy resin, polished to a thickness of 110 μm; cover the second matching layer on the first matching layer.

[0055] Preparation of the flexible backing layer: The flexible backing layer is a mixture of composite soft glue, tungsten powder, hollow glass powder, and silica, and the weight ratio of composite soft glue, tungsten powder, hollow glass powder, and silica is 1:1:0.3:0.05; the composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:6; pour the flexible backing layer on the back of the flexible circuit board, and the thickness of the flexible backing layer is 3 mm.

[0056] Embodiment 3

[0057] This embodiment is the application of the wearable ultrasonic transducer of the bionic Venus flytrap in Embodiment 1 in ultrasonic imaging during thyroid nodule puncture biopsy. This wearable ultrasonic transducer has high resolution, a wide imaging field of view, and good skin curvature adaptability. As Figure 6 shown, by simultaneously imaging in two sections, it can effectively guide the puncture biopsy surgery of thyroid nodules, reduce the surgical difficulty, and improve the surgical precision. This transducer has good electrical and acoustic properties, can meet the clinical needs, and has broad application prospects.

[0058] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A wearable ultrasonic transducer imitating a Venus flytrap, characterized in that, It includes a flexible circuit board and two linear arrays with the same structure and size located on the flexible circuit board; The linear array is a 64-element linear array with an element pitch of 220 μm; the linear array includes a signal electrode, a piezoelectric composite layer, a ground electrode, and a matching layer stacked from bottom to top; the flexible circuit board is provided with leads that are electrically connected to the signal electrode in a matching manner; There is a gap between the two linear arrays, such that when the flexible circuit board is bent, the upper surfaces of the two linear arrays approach each other and the planes where the upper surfaces of the two linear arrays are located form an angle.

2. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 1, characterized in that, The piezoelectric composite layer is a 1-3 piezoelectric composite, and this 1-3 piezoelectric composite is a ceramic material, having a number of parallel slits and forming a number of parallel piezoelectric ceramic strips in two adjacent slits, each piezoelectric ceramic strip having a width of 90 μm and each slit having a width of 20 μm.

3. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 1, wherein The matching layer is divided into two layers, including a first matching layer covering the ground electrode and a second matching layer covering the first matching layer; the first matching layer is a mixture of epoxy resin and alumina powder, and the weight ratio of epoxy resin to alumina powder is 1:1.2; the second matching layer is pure epoxy resin.

4. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 3, characterized in that, The back surface of the flexible circuit board is further provided with a flexible backing layer, and the flexible backing layer is a mixture of composite soft glue, tungsten powder, hollow glass powder, and silica, and the weight ratio of composite soft glue, tungsten powder, hollow glass powder, and silica is 1:1:0.3:0.05; the composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:

6.

5. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 3, wherein, The gap width between the two linear arrays is 4 mm; the thickness of the piezoelectric composite layer is 260 μm, the thickness of the first matching layer is 140 μm, and the thickness of the second matching layer is 110 μm; The thickness of the signal electrode is 20 μm, and the thickness of the ground electrode is 20 μm.

6. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 2, characterized in that, The slits are filled with epoxy resin.

7. The wearable ultrasonic transducer of the bionic Venus flytrap according to claim 1, characterized in that, The two linear arrays are used to perform ultrasonic imaging on two sections simultaneously.

8. A method for preparing a wearable ultrasonic transducer of the bionic Venus flytrap according to any one of claims 1 to 7, characterized in that, It includes: Preparation of the piezoelectric composite layer: Cut the piezoelectric composite with a cutting pitch of 110 μm and a slit width of 20 μm; Fill the slits with epoxy resin and cure at room temperature; subsequently, grind the piezoelectric composite to a thickness of 260 μm, sputter a 50-nm Cr layer first on one side of the piezoelectric material, then sputter a 200-nm Au layer, and then sputter a 50-nm Cr layer first on the other side of the piezoelectric material and then sputter a 200-nm Au layer; Preparation of the matching layer: Divide the matching layer into two layers, the first matching layer is a mixture of epoxy resin and alumina powder, and the weight ratio of epoxy resin to alumina powder is 1:1.2; Centrifuge this mixture at a centrifugal speed of 3000 r / min for 15 minutes, then post-cure and polish to a thickness of 140 μm; the second matching layer is pure epoxy resin, polished to a thickness of 110 μm; Cover the second matching layer on the first matching layer.

9. The preparation method according to claim 8, characterized in that, The back of the flexible circuit board is also provided with a flexible backing layer, which is a mixture of composite soft glue, tungsten powder, hollow glass powder, and silicon dioxide. The weight ratio of the composite soft glue, tungsten powder, hollow glass powder, and silicon dioxide is 1:1:0.3:0.05; the composite soft glue is a mixture of PDMS and Ecoflex, and the weight ratio of PDMS to Ecoflex is 4:6; The flexible backing layer is cast on the back of the flexible circuit board, and the thickness of the flexible backing layer is 3 mm.

10. Application of the wearable ultrasonic transducer of the bionic Venus flytrap as described in claim 1 in ultrasonic imaging during thyroid nodule puncture biopsy.

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