Flexible variable-curvature phased array probe based on 3D printing and preparation method thereof

Abstract

The invention relates to the technical field of flexible transducers capable of dynamically expanding an imaging view field, and discloses a flexible variable-curvature phased array probe based on 3D printing and a preparation method thereof. The technical problem that in the prior art, due to the fact that a traditional rigid transducer is fixed in shape and size in the manufacturing process, the imaging view angle is fixed, and then the application effect in human kidney imaging is affected is solved. The preparation method of the flexible variable-curvature phased array probe based on 3D printing comprises the following steps: preparing a piezoelectric layer; preparing a double-layer composite backing; changing the curvature of the probe; performing 3D printing on the flexible printed circuit board; and connecting the piezoelectric layer array element with the flexible circuit board. By preparing the flexible variable-curvature phased array probe, the visual angle problem is effectively solved, and the application effect in human kidney imaging is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible transducers with dynamically expandable imaging fields of view, and in particular to a flexible variable curvature phased array probe based on 3D printing and a preparation method thereof. Background Art

[0002] Ultrasound imaging can provide doctors with intrinsic, non-destructive and high-resolution pathological behaviors to guide the treatment and prognosis of diseases due to its advantages such as non-invasiveness, excellent real-time performance and multiple biological effects. The wider imaging field of view of the transducer can capture more complete organs. However, traditional commercial transducers are presented in a rigid form. The imaging aperture expands the imaging field of view by increasing the number of array elements. The increased channels will produce a larger volume and use cost. Another method is to bend the transducer to expand the wide imaging field of view. The shape of the convex array probe is fixed during manufacturing. Although traditional commercial transducers have high mechanical strength and stable transducer performance, their imaging field of view limits the scope of visualization.

[0003] However, during the implementation of the above scheme, there are at least the following technical problems: the traditional rigid transducer has a fixed imaging angle of view due to its fixed shape and size during manufacturing, which in turn affects the application effect in human kidney imaging. Therefore, a method to expand the imaging field of view of medical ultrasound probes is to realize the variable curvature deformation and imaging function from linear array to convex array through a 3D printing device, and dynamically expand a wider imaging field of view. In clinical use, this flexible variable curvature phased array probe (FPAP) can adapt to different fat and thin people by changing the curvature of the probe, so as to have a suitable imaging field of view and imaging depth. In addition, a wider imaging field of view is also necessary for obese people because they have a larger abdominal cavity space and a thicker fat layer. The expandable imaging field of view function of FPAP can be applied to patients with different BMIs, thereby improving the quality and accuracy of ultrasound imaging. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a flexible variable curvature phased array probe based on 3D printing and a preparation method thereof, which solves the problem in the prior art that the traditional rigid transducer has a fixed imaging angle due to its fixed shape and size during manufacturing, thereby affecting the application effect in human kidney imaging. By preparing a flexible variable curvature phased array probe, the angle problem is effectively solved and the application effect in human kidney imaging is significantly improved.

[0005] According to one aspect of the present disclosure, a flexible variable curvature phased array probe based on 3D printing is provided, and a method for preparing a flexible variable curvature phased array probe based on 3D printing comprises the following steps: (1) Preparation of piezoelectric layer: a. First, select the base material: use PZT-5H lead zirconate titanate material; b. Prepare the composite material: use the dice-filling technology to prepare 1-3 type piezoelectric composite materials to form a piezoelectric layer; c. Fill the piezoelectric layer with resin, and the piezoelectric layer includes a plurality of array elements; (2) Preparing a double-layer composite backing: a. Preparing a rigid backing layer: using epoxy resin and aluminum oxide to prepare a rigid backing layer; b. Preparing a flexible backing layer: using epoxy resin to prepare a flexible backing layer for direct contact with the skin; (3) The probe has a variable curvature. The array elements described in step (1) are separated using the aligned double-cutting process. Eeo-flex and RTVSealant 734 sealing glue are mixed into two different composite two-component substrates in a ratio of 6:4 and 5:5 respectively. a. First cutting and filling: Use saw teeth to cut the piezoelectric layer array elements at equal intervals on the array element matching surface. Use a 6:4 viscoelastic composite substrate to fill the cuts to prevent adjacent array elements from debonding when the array is bent and to provide mechanical support for the second complete cutting. b. Second aligned cutting and filling: Use the aligned cutting process to completely separate the independent array elements on the array element backing surface. Use a 5:5 viscoelastic composite substrate with a high elastic modulus to fill the cuts so that the bottom of the array element can fully rebound after bending. (4) 3D printed flexible printed circuit board: Use a mixture of polydimethylsiloxane and alumina to cast a flexible circuit board, and encapsulate it with a PET film. The flexible backing layer is coupled with the 3D printed piezoelectric layer array element. Double rows of holes are punched on the PET film and integrated into the 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retracting mechanical claw. (5) Connecting the piezoelectric array element to the flexible circuit board: Connect the bottom electrode of the piezoelectric array element to the corresponding electrode of the flexible circuit board; stimulate the flexible circuit board to make the piezoelectric array element work; and achieve precise positioning of the flexible array element through shape sensing optical fiber.

[0006] In some embodiments of the present disclosure, the PZT-5H lead zirconate titanate material in step (1) is 3203HD.

[0007] In some embodiments of the present disclosure, in step (1), the width of the array element is 75 μm, and the distance between adjacent array elements is 24 μm.

[0008] In some embodiments of the present disclosure, the resin in step (1) is Epo-Tek 301 epoxy resin. After filling the resin in step c, the step of double-sided grinding is also included, in which the lead zirconate titanate filled with the resin is double-sided ground to a thickness of 0.6 mm.

[0009] In some embodiments of the present disclosure, the number of array elements in step (1) is 128.

[0010] In some embodiments of the present disclosure, in step (2), the rigid backing layer has a thickness of 275 μm, and the flexible backing layer has a thickness of 200 μm.

[0011] In some embodiments of the present disclosure, the step between step (2) and step (3) also includes casting a 0.4 mm conductive backing using E-solder material, and cutting a groove with a length of 46.08 mm and a depth of 0.25 mm in the bending direction of the array, i.e., the azimuth direction.

[0012] In some embodiments of the present disclosure, in step (3), saw teeth are used to cut the array elements at equal intervals, and after cutting, the width of the array elements is 0.36 mm and the depth is 0.6 mm.

[0013] In some embodiments of the present disclosure, the particle size of the aluminum oxide mixture in step (4) is 6 μm; and the thickness of the PET film is 0.8 mm.

[0014] A flexible variable curvature phased array probe based on 3D printing is prepared by the above-mentioned method for preparing a flexible variable curvature phased array probe based on 3D printing, comprising a double-layer composite backing, the double-layer composite backing comprising a rigid backing layer and a flexible backing layer, the flexible backing layer is coupled to connect the piezoelectric layer array element, a flexible printed circuit board is installed in the flexible backing layer, a PET film is packaged on the outside of the flexible printed circuit board, a double row of array holes is punched on the PET film, the flexible printed circuit board is integrated on a variable curvature push rod, the variable curvature push rod comprises a telescopic push rod, and the telescopic push rod comprises a A circular pushing portion in the middle of the flexible printed circuit board is pushed to form a convex array structure to achieve dynamic expansion of the imaging field of view. The circular pushing portion is installed in the square structure. The circular pushing portion is connected to a columnar pushing portion at one end away from the flexible printed circuit board. Both ends of the columnar pushing portion are connected to a pull rope fixing member via a pull rope. Both ends of the pull rope are fixedly installed on both ends of the flexible printed circuit board. The electrodes of the flexible printed circuit board are connected to the array elements of the piezoelectric layer. The array elements are filled with a two-component substrate. The two-component substrate includes a viscoelastic composite substrate and an elastic glue, and the filling ratio is 7:3.

[0015] The beneficial effects of the present invention are: 1. The probe realizes the curvature deformation and imaging function of the imaging field of the flexible probe end from the linear array to the convex array through the push-pull action of the 3D printing device, dynamically expanding the wider imaging field of view. The low-frequency and too thick piezoelectric stack innovatively uses the double-cut process to divide the array elements to realize the 0.7λ spacing phased array, and for the first time fills the prefabricated two-component viscoelastic substrate to realize the tensile stress and compressive stress generated during deformation. The low-frequency piezoelectric ultrasonic wave is too long, and the backing layer after use can effectively absorb the sound wave to increase the bandwidth, so as to improve the axial resolution and imaging quality. The rigid-flexible double-back composite lining is designed to expand the bandwidth while ensuring mechanical flexibility, resulting in a high bandwidth of -6dB~78% and a low crosstalk of -50dB.

[0016] 2. When the push rod is not used, the flexible transducer is close to the square structure, providing sufficient mechanical support for abdominal detection; when the circular push rod is pushed out, the flexible transducer is pushed to evenly deform into a convex array structure to achieve dynamic expansion of the imaging field of view. Good imaging effects have been achieved in dynamic wide-field imaging of the abdomen, providing strong support for clinical diagnosis.

[0017] 3. The probe achieves dynamic variable curvature imaging through a 3D printing device, expanding the imaging field of view, thus meeting the clinical medical needs of ultrasound abdominal imaging. The combination of a phased array flexible convex array probe and a Vantage multi-channel system signal acquisition system can achieve high-resolution, high-sensitivity imaging effects, and has good bending performance. It is suitable for the main abdominal organs of different fat and thin people with a suitable imaging field of view and a large imaging depth.

[0018] 4. Use 3D printed variable curvature devices to improve reliability, and change the tensile stress and compressive stress generated during deformation by modulating the two-component viscoelastic substrate.

[0019] 5. The effective double-layer composite backing 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 the imaging quality. Using E-solder material to cast a 0.4mm conductive backing and making a groove in the azimuth direction can not only effectively reduce the ringing effect and increase the bandwidth, but also make the OSS shape sensing fiber conformally contact with any array element to improve the spatial positioning accuracy.

[0020] 6. Use the double-cut process to divide 128 array elements, and fill the two-component substrate in a ratio of 7:3. On the one hand, it can achieve satisfactory sound attenuation to reduce crosstalk between array elements, and on the other hand, it can provide reliable mechanical support for the second cutting to completely divide the array elements. Filling with elastic glue allows the array elements to maintain effective rebound after bending.

[0021] 7. The backing layer can provide sufficient acoustic wave attenuation, shorten the vibration length, increase the bandwidth, and suppress the ringing effect to broaden the bandwidth. The backing layer is coupled with the piezoelectric layer array element to provide sufficient mechanical support for FPAP biological imaging of arbitrary curvature, and can provide conformal contact during array bending detection. Double rows of holes are punched on the PET film and integrated into the 3D printed variable curvature push rod. The curvature of the soft probe can be changed by the push rod and the retracted mechanical claw, and the imaging field of view is effectively expanded from 90 degrees to 180 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the internal structure of a flexible variable curvature phased array probe based on 3D printing; Figure 2 Bending stress diagram for different curvatures; Figure 2 a is the stress diagram when bending with a curvature of 0°, b is the stress diagram when bending with a curvature of 90°, c is the stress diagram when bending with a curvature of 60°, and d is the stress diagram when bending with a curvature of 120°. Figure 3 Acquire pattern resolution and contrast images for flexible variable curvature probes; Figure 4 Comparison of abdominal renal imaging with a flexible variable curvature probe and a commercial convex array probe; Figure 5 It is a schematic diagram of the three-dimensional structure of a variable curvature push rod; Figure 6 This is a reference diagram of the state of the circular push part of the variable curvature push rod when it is ejected; Figure 7 This is a reference diagram of the state when the circular push portion of the variable curvature push rod is contracted; The names of the components in the figure are: 1. telescopic push rod; 2. flexible printed circuit board; 3. circular push part; 4. square structure; 5. cylindrical push part; 6. pull rope; 7. pull rope fixing part; 8. array element; 9. elastic glue; 10. PET film; 11. flexible backing layer; 12. piezoelectric composite material; 13. rigid backing layer; 14. flexible backing layer; 15. flexible circuit board. DETAILED DESCRIPTION

[0023] 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

[0024] This example discloses a flexible variable curvature phased array probe based on 3D printing and a preparation method thereof, see Figures 1 to 7 A method for preparing a flexible variable curvature phased array probe based on 3D printing comprises the following steps: (1) Preparation of piezoelectric layer: a. First, select the base material: use PZT-5H lead zirconate titanate material; b. Prepare the composite material: use the dice-filling technology to prepare the 1-3 type piezoelectric composite material 12 to form a piezoelectric layer; c. Fill the piezoelectric layer with resin, and the piezoelectric layer includes a plurality of array elements; (2) Preparing a double-layer composite backing, a. Preparing a rigid backing layer 13: using epoxy resin and aluminum oxide to prepare a rigid backing layer; b. Preparing a flexible backing layer 14: using epoxy resin to prepare a flexible backing layer to directly contact the skin; (3) The probe has a variable curvature. The array elements described in step (1) are separated using the aligned double-cutting process. Eeo-flex and RTVSealant 734 sealing glue are mixed into two different composite two-component substrates in a ratio of 6:4 and 5:5 respectively. a. First cutting and filling: Use saw teeth to cut the piezoelectric layer array elements at equal intervals on the array element matching surface. Use a 6:4 viscoelastic composite substrate to fill the cuts to prevent adjacent array elements from debonding when the array is bent and to provide mechanical support for the second complete cutting. b. Second aligned cutting and filling: Use the aligned cutting process to completely separate the independent array elements on the array element backing surface. Use a 5:5 viscoelastic composite substrate with a high elastic modulus to fill the cuts so that the bottom of the array element can fully rebound after bending. (4) 3D printed flexible printed circuit board 15: A flexible circuit board 15 is cast using a mixture of polydimethylsiloxane and alumina, and is encapsulated with a PET film. The flexible backing layer is coupled with the 3D printed piezoelectric layer array element, and double-row array holes are punched on the PET film and integrated into a 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retracting mechanical claw. (5) Connecting the piezoelectric layer array element to the flexible circuit board 15: Connecting the bottom electrode of the piezoelectric layer array element to the electrode of the flexible circuit board correspondingly; exciting the flexible circuit board to make the piezoelectric array element work; and realizing the precise positioning of the flexible array element through the shape sensing optical fiber.

[0025] In step (1), the PZT-5H lead zirconate titanate material is 3203HD.

[0026] In step (1), the width of the array element is 75 μm, and the distance between adjacent array elements is 24 μm.

[0027] The resin in step (1) is Epo-Tek 301 epoxy resin. After filling the resin in step c, the step of double-sided polishing is also included, in which the lead zirconate titanate filled with the resin is double-sided polished to a thickness of 0.6 mm.

[0028] In step (1), the number of array elements is 128.

[0029] In step (2), the thickness of the rigid backing layer is 275 μm, and the thickness of the flexible backing layer is 200 μm.

[0030] Between step (2) and step (3), the method further includes using E-solder material to cast a 0.4 mm conductive backing, and cutting a groove with a length of 46.08 mm and a depth of 0.25 mm in the bending direction of the array, i.e., the azimuth direction.

[0031] In step (3), the array elements are cut at equal intervals using saw teeth. After cutting, the width of the array elements is 0.36 mm and the depth is 0.6 mm.

[0032] In step (4), the particle size of the aluminum oxide mixture is 6 μm; the thickness of the PET film is 0.8 mm.

[0033] A flexible variable curvature phased array probe based on 3D printing is prepared by the above-mentioned flexible variable curvature phased array probe preparation method based on 3D printing, including a double-layer composite backing, the double-layer composite backing includes a rigid backing layer and a flexible backing layer, the flexible backing layer is coupled to connect the piezoelectric layer array element, a flexible printed circuit board is installed in the flexible backing layer 11, a PET film 10 is packaged outside the flexible printed circuit board, a double row of alignment holes is punched on the PET film 10, a flexible printed circuit board 2 is integrated on a variable curvature push rod, the variable curvature push rod includes a telescopic push rod 1, and the telescopic push rod 1 includes a A circular pushing portion 3 in the middle of the flexible printed circuit board 2 is pushed to form a convex array structure to achieve dynamic expansion of the imaging field of view. The circular pushing portion 3 is installed in the square structure 4. The circular pushing portion 3 is connected to a columnar pushing portion 5 at one end away from the flexible printed circuit board. Both ends of the columnar pushing portion 5 are connected to a pull rope fixing member 7 via a pull rope 6. Both ends of the pull rope 6 are fixedly installed on both ends of the flexible printed circuit board 2. The electrodes of the flexible printed circuit board 2 are connected to an array element 8 of the piezoelectric layer. The array element 8 is filled with a two-component substrate. The two-component substrate includes a viscoelastic composite substrate and an elastic glue 9, and the filling ratio is 7:3.

[0034] The 3MHz, 128-element flexible variable curvature phased array probe (FPAP) made based on 3D printing technology is used for dynamic wide-field imaging of the abdomen. The flexible probe realizes the variable curvature deformation and imaging function from the imaging field of the flexible probe end from the linear array to the convex array through the push-pull action of the 3D printing device, dynamically expanding the wider imaging field of view. The low-frequency and too thick piezoelectric stack innovatively uses the counter-position double-cut process to divide the array elements to realize the 0.7λ spacing phased array, and the prefabricated two-component viscoelastic substrate is filled for the first time to realize the tensile stress and compressive stress generated during deformation. The low-frequency piezoelectric ultrasound wave is too long, and the backing layer after use can effectively absorb the sound wave to increase the bandwidth, so as to improve the axial resolution and imaging quality. We innovatively designed a rigid-flexible double-back composite lining to expand the bandwidth while ensuring mechanical flexibility, resulting in a high bandwidth of -6dB~78% and a low crosstalk of -50dB.

[0035] Structural innovation: We designed a 3D printed push-pull device consisting of a circular retractable push rod, a square structure and a pull rope. When the push rod is not in use, the flexible transducer is close to the square structure, providing sufficient mechanical support for abdominal detection; when the circular push rod is pushed out, it pushes the flexible transducer to evenly deform into a convex array structure to achieve dynamic expansion of the imaging field of view.

[0036] Results: The present invention adopts a flexible phased array probe combined with a multi-channel signal acquisition system, which can achieve high-resolution and high-sensitivity imaging effects, and has good bending performance to expand the imaging field of view, which is suitable for different fat and thin people to examine the main abdominal organs. The experimental results show that this method has achieved good imaging effects in dynamic wide-field imaging of the abdomen, providing strong support for clinical diagnosis. The results show that the excellent mechanical deformation of FPAP meets the minimum curvature radius of 12mm, and the expandable imaging field of view ranges from 0° to 120°. The axial and lateral resolutions of the near-field (30mm), focal (50) and far-field (80mm) line target imaging in the commercial phantom are 0.34mm and 0.36mmmm, 0.34mm and 0.55mm, 0.35mm and 0.77mm, respectively. Finally, the B-mode images of the kidneys were collected from the abdomen of adult males with different BMIs of 15.7, 20.9 and 28.1, and the renal sinus structures such as the renal columns, renal pyramids, and renal cortex of the kidneys were clearly collected. In addition, B-mode images of the uterus and bladder were acquired in an adult female with a BMI of 21.9.

[0037] The problem of fixed imaging angle of view of traditional rigid transducers due to their fixed shape and size during manufacturing is solved by preparing a flexible variable curvature phased array probe, which effectively solves the angle problem and significantly improves the application effect in human kidney imaging.

[0038] 3MHz, 128-element flexible variable curvature phased array probe, which realizes dynamic variable curvature imaging through 3D printing device, expands the imaging field of view, and thus meets the clinical medical needs of ultrasound abdominal imaging. The combination of phased array flexible convex array probe and Vantage multi-channel system signal acquisition system can achieve high-resolution, high-sensitivity imaging effects, and has good bending performance. It is suitable for the main abdominal organs of different fat and thin people with suitable imaging field of view and large imaging depth.

[0039] The flexible variable curvature phased array probe consists of three modules: piezoelectric stack, rigid-flexible double backing layer and 3D printing device. The rigid-flexible double backing layer consists of E-solder rigid backing and self-developed high-attenuation composite flexible backing layer. During the preparation process, the dice-filling technology is used to prepare high-performance 1-3 piezoelectric composite materials, and the array elements and rigid backing layer are divided by the double-cut process. In addition, a 3D printed variable curvature device is used to provide a reliable machine and solve the tensile stress and compressive stress generated during deformation through a modulated two-component viscoelastic substrate. Finally, it is concluded that the mechanical deformation of FPAP meets the minimum conformal curvature radius of 12mm and the curvature range of the variable imaging field of view of 0°~120° deflection. Preparation of piezoelectric layer: The piezoelectric layer uses PZT-5H lead zirconate titanate (3203HD) material, and uses dice-filling technology to prepare 1-3 piezoelectric composite materials. The array width is 75μm, the slit is 24μm, and the thick double-sided polishing to a thickness of 0.6mm after filling with resin (Epo-Tek 301). The result is a volume fraction of up to 57.8%, a volume fraction of 57.8% and a thickness-to-width ratio of 8 (0.6 / 0.075mm). 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, an effective matching layer can perfectly match the acoustic impedance with the outer interface of the skin, effectively improving the efficiency of sound wave transmission so that more sound waves can penetrate into the human skin to improve imaging quality. The flexible variable curvature phased array probe adopts a double-layer composite backing design. The first layer is matched with epoxy-alumina to prepare a conductive matching layer with a thickness of 275μm, and the second layer is matched to directly contact the skin and is made of pure epoxy resin with a thickness of 200μm. In addition, the use of E-solder material to cast a 0.4mm conductive backing and make a groove in the azimuth direction can not only effectively reduce the ringing effect and increase the bandwidth, but also make the OSS shape sensing fiber conformally contact with any array element to improve the spatial positioning accuracy.

[0040] FPAP's variable curvature implementation process: 128 array elements are divided using a counter-positioned double-cut process, and a two-component substrate is filled in a ratio of 7:3. On the one hand, satisfactory acoustic attenuation can be achieved to reduce crosstalk between array elements, and on the other hand, reliable mechanical support can be provided for the second cut to completely divide the array elements. Use a 0.3mm sawtooth to perform equidistant cutting at a depth of 0.36 pitch and o.6mm. Use a viscoelastic composite substrate with excellent bonding force to prevent debonding of adjacent array elements and perform the first filling. Secondly, the backing surface uses counter-positioned cutting to divide independent array elements, and is filled with elastic glue, which allows the array elements to maintain effective rebound after bending. Finally, at a depth of 0.4mm, the E-solder cuts 0.25mm deep along the azimuth direction to provide a compatible platform for the optical fiber. This process can provide excellent mechanical support and acoustic optimization for flexible convex arrays.

[0041] Rigid-flexible double backing layer and 3D printing device: The complete backing layer is cast on the flexible circuit board FPC using a mixture of PDMS and 6μm alumina particles and encapsulated with 0.8mm PET, which can provide sufficient acoustic wave attenuation, reduce the vibration length, and increase the bandwidth. The thickness of the entire flexible backing layer is 4mm, which can provide sufficient acoustic attenuation and suppress the ringing effect to broaden the bandwidth. The backing layer is coupled with the 3D printed piezoelectric layer array element, which can provide sufficient mechanical support for FPAP biological imaging of arbitrary curvature and provide conformal contact when the array is bent. In addition, double rows of holes are punched on the PET film and integrated into the 3D printed variable curvature push rod. The curvature of the soft probe can be changed by the push rod and the retracted mechanical claw, and the imaging field of view is effectively expanded from 90 degrees to 180 degrees.

[0042] The flexible variable curvature phased array probe can realize the variable curvature deformation and imaging function from linear array to convex array, dynamically expand the wider imaging field of view, and use the double-cut process to divide the array elements to realize the 0.7λ spacing phased array, and fill the prefabricated two-component viscoelastic substrate to solve the tensile stress and extrusion stress generated during deformation. In addition, the rigid-flexible double backing layer is innovatively designed to expand the bandwidth -6dB~78% and low crosstalk -50dB while ensuring mechanical flexibility. The 3D printed variable curvature device is used to provide reliable mechanical support. The results show that the excellent mechanical deformation of FPAP meets the minimum curvature radius of 12mm, and the variable curvature range is 0°~120° deflection. The axial and lateral resolutions of the commercial phantom imaging of the linear target are 3mm and 4.2mm respectively. With its expandable imaging field of view function, it can improve the quality and accuracy of ultrasound imaging and help doctors better detect the pathological behavior of tissues or organs.

[0043] Working mode of flexible variable curvature phased array probe: The bottom electrodes of each column of piezoelectric array elements are connected to the electrodes of the FPC flexible circuit board one by one, so that the electrodes of each column of piezoelectric array elements are electrically connected to the array on the FPC board; by stimulating the FPC flexible circuit board, all piezoelectric array elements can be stimulated to make them work.

[0044] The flexible array element is precisely positioned through shape sensing optical fiber, and an E-solder is used to cut 0.25mm along the azimuth direction to provide a compatible platform for the optical fiber. The precise positioning of the ground error obtained by building a system to analyze the optical fiber can further improve the quality and accuracy of ultrasonic imaging.

[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 method for preparing a flexible variable curvature phased array probe based on 3D printing, characterized in that: The steps include: (1) Preparation of piezoelectric layer: a. First, select the base material: use PZT-5H lead zirconate titanate material; b. Prepare the composite material: use the dice-filling technology to prepare 1-3 type piezoelectric composite materials to form a piezoelectric layer; c. Fill the piezoelectric layer with resin, and the piezoelectric layer includes a plurality of array elements; (2) Preparing a double-layer composite backing: a. Preparing a rigid backing layer: using epoxy resin and aluminum oxide to prepare a rigid backing layer; b. Preparing a flexible backing layer: using epoxy resin to prepare a flexible backing layer for direct contact with the skin; (3) The probe has a variable curvature. The array elements described in step (1) are separated by a double-cutting process. The elastic sealant and the single-component room temperature vulcanized silicone rubber sealant are mixed in a ratio of 6:4 and 5:5 to form two different composite two-component substrates. The elastic sealant is Eeo-flex, and the single-component room temperature vulcanized silicone rubber sealant is RTV Sealant 734 sealing glue. a. First cutting and filling: Use saw teeth to cut the piezoelectric layer array elements at equal intervals on the array element matching surface. Use a 6:4 viscoelastic composite substrate to fill the cuts to prevent adjacent array elements from debonding when the array is bent and to provide mechanical support for the second complete cutting. b. Secondary alignment cutting and filling: Use an alignment cutting process to completely separate the independent array elements on the backing surface of the array element. Use a 5:5 viscoelastic composite substrate with a high elastic modulus to fill the cuts so that the bottom of the array element can fully rebound after bending. (4) 3D printed flexible printed circuit board: A flexible circuit board is cast using a mixture of polydimethylsiloxane and alumina and encapsulated with a PET film. The flexible backing layer is coupled with the 3D printed piezoelectric layer array element. Double rows of holes are punched on the PET film and integrated into the 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retracting mechanical claw. (5) Connecting the piezoelectric layer array element to the flexible circuit board: Connecting the bottom electrode of the piezoelectric layer array element to the electrode of the flexible circuit board accordingly; stimulating the flexible circuit board to make the piezoelectric array element work; Accurate positioning of flexible array elements is achieved through shape sensing optical fiber.

2. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: In the step (1), the PZT-5H lead zirconate titanate material is 3203HD.

3. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: In step (1), the width of the array element is 75 μm, and the distance between adjacent array elements is 24 μm.

4. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: The resin in step (1) is Epo-Tek 301 epoxy resin. After filling the resin in step c, the step of double-sided polishing is also included, in which the lead zirconate titanate filled with the resin is double-sided polished to a thickness of 0.6 mm.

5. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: In step (1), the number of array elements is 128.

6. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: In the step (2), the thickness of the rigid backing layer is 275 μm, and the thickness of the flexible backing layer is 200 μm.

7. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: The step between step (2) and step (3) also includes using E-solder material to cast a 0.4 mm conductive backing, and cutting a groove with a length of 46.08 mm and a depth of 0.25 mm in the bending direction of the array, i.e., the azimuth direction.

8. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: In the step (3), saw teeth are used to cut the array elements at equal intervals, and after cutting, the width of the array elements is 0.36 mm and the depth is 0.6 mm.

9. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: The particle size of the aluminum oxide mixture in step (4) is 6 μm; the thickness of the PET film is 0.8 mm.

10. A flexible variable curvature phased array probe based on 3D printing, made by the method for making a flexible variable curvature phased array probe based on 3D printing according to claim 1, characterized in that: The invention comprises a double-layer composite backing, wherein the double-layer composite backing comprises a rigid backing layer and a flexible backing layer, wherein the flexible backing layer is coupled to connect the piezoelectric layer array element, wherein a flexible printed circuit board is arranged inside the flexible backing layer, wherein a PET film is encapsulated outside the flexible printed circuit board, wherein a double row of array holes are punched on the PET film, wherein the flexible printed circuit board is integrated on a variable curvature push rod, wherein the variable curvature push rod comprises a telescopic push rod, wherein the telescopic push rod comprises a circular push portion capable of pushing the middle part of the flexible printed circuit board to form a convex array structure and realize dynamic expansion of the imaging field of view, wherein the circular push portion is arranged in a square structure, wherein the circular push portion is connected to a columnar push portion at one end away from the flexible printed circuit board, wherein two ends of the columnar push portion are connected to a pull rope fixing member via a pull rope, wherein two ends of the pull rope are fixedly mounted on two ends of the flexible printed circuit board, wherein electrodes of the flexible printed circuit board are connected to the array element of the piezoelectric layer, wherein the array element is filled with a two-component substrate, wherein the two-component substrate comprises a viscoelastic composite substrate and an elastic glue, and the filling ratio is 7:3.

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