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

Abstract

The present invention relates to the technical field of flexible transducers with dynamically expandable imaging fields of view, and discloses a flexible variable curvature phased array probe based on 3D printing and a method for preparing the same. The invention aims to solve the problem in the prior art that the imaging viewing angle of traditional rigid transducers is fixed due to their fixed shape and size during manufacturing, thereby affecting the technical problem of their application effect in human kidney imaging. The method for preparing a flexible variable curvature phased array probe based on 3D printing of the present invention comprises: preparing a piezoelectric layer; preparing a double-layer composite backing; changing the curvature of the probe; 3D printing a flexible printed circuit board; and connecting the piezoelectric layer array element to the flexible circuit board. The present invention effectively solves the viewing angle problem and significantly improves the application effect in human kidney imaging by preparing a flexible variable curvature phased array probe.

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, due to its advantages such as non-invasiveness, excellent real-time performance, and multiple biological effects, can provide doctors with intrinsic, non-destructive, and high-resolution pathological behaviors to guide disease treatment and prognosis. The wider imaging field of view of the transducer can capture more complete organs. However, traditional commercial transducers are all 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 result in a larger volume and usage cost. Another method is to bend the transducer to expand the 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 transduction performance, their imaging field of view limits the range of visualization.

[0003] However, the implementation of the above solution presents at least the following technical issues: Traditional rigid transducers, due to their fixed shape and size during manufacturing, have a fixed imaging angle of view, which in turn affects their effectiveness in imaging the human kidney. Therefore, one approach to expanding the imaging field of view of medical ultrasound probes is to use 3D printing to achieve variable curvature deformation and imaging capabilities from a linear array to a convex array, dynamically expanding the imaging field of view. In clinical use, this flexible variable curvature phased array probe (FPAP) can adapt to different individuals by changing the probe's curvature, thereby providing an appropriate imaging field of view and depth. Furthermore, a wider imaging field of view is necessary for obese individuals, as they have a larger abdominal cavity and a thicker fat layer. The FPAP's expandable imaging field of view can be adapted to patients with varying BMIs, thereby improving the quality and accuracy of ultrasound imaging. Summary of the Invention

[0004] In response to the above technical issues, the present invention provides a flexible, variable-curvature phased array probe based on 3D printing and a method for its fabrication. This approach addresses the existing problem of traditional rigid transducers, whose fixed shape and size during manufacturing result in a fixed imaging perspective, thus hindering their effectiveness in kidney imaging. By fabricating a flexible, variable-curvature phased array probe, the perspective issue is effectively resolved and the effectiveness of 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:

[0006] (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 technique 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 several array elements;

[0007] (2) Preparation of a double-layer composite backing: a. Preparation of a rigid backing layer: using epoxy resin and aluminum oxide to prepare a rigid backing layer; b. Preparation of a flexible backing layer: using epoxy resin to prepare a flexible backing layer for direct contact with the skin;

[0008] (3) The probe has a variable curvature. The array elements described in step (1) are separated using a 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 a sawtooth to cut the piezoelectric layer array elements at equal intervals on the array element matching surface. Fill the cut with a 6:4 viscoelastic composite substrate to prevent adjacent array elements from debonding when the array is bent and 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. Fill the cut with a 5:5 viscoelastic composite substrate with a high elastic modulus so that the bottom of the array element can fully rebound after bending.

[0009] (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 a 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retraction of the mechanical claw.

[0010] (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.

[0011] In some embodiments of the present disclosure, the PZT-5H lead zirconate titanate material in step (1) is 3203HD.

[0012] 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.

[0013] 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 also includes a double-sided polishing step, in which the lead zirconate titanate filled with the resin is polished on both sides to a thickness of 0.6 mm.

[0014] In some embodiments of the present disclosure, the number of array elements in step (1) is 128.

[0015] In some embodiments of the present disclosure, the thickness of the rigid backing layer in step (2) is 275 μm, and the thickness of the flexible backing layer is 200 μm.

[0016] In some embodiments of the present disclosure, the step between step (2) and step (3) further 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.

[0017] 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 array elements have a width of 0.36 mm and a depth of 0.6 mm.

[0018] 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.

[0019] A flexible variable curvature phased array probe based on 3D printing is made 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 being coupled to connect the piezoelectric layer array element, a flexible printed circuit board being installed in the flexible backing layer, the flexible printed circuit board being externally encapsulated with a PET film, the PET film being provided with double rows of alignment holes, the flexible printed circuit board being integrated on a variable curvature push rod, the variable curvature push rod comprising a telescopic push rod, the telescopic push rod comprising A circular pushing portion is provided to push the middle part of the flexible printed circuit board to form a convex array structure, thereby dynamically expanding the imaging field of view. The circular pushing portion is installed in the square structure, and the circular pushing portion is connected to the cylindrical pushing portion at one end away from the flexible printed circuit board. The two ends of the cylindrical pushing portion are connected to the rope fixing member via a pull rope, and the two ends of the pull rope are fixedly installed at the two 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, and 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.

[0020] The beneficial effects of the present invention are:

[0021] 1. The probe achieves variable curvature deformation and imaging capabilities from a linear array to a convex array at the flexible probe end through the push-pull action of a 3D-printed device, dynamically expanding the imaging field of view. The thick low-frequency piezoelectric stack innovatively uses a double-cut process to separate the array elements to achieve a 0.7λ pitch phased array. For the first time, a prefabricated two-component viscoelastic substrate is filled to generate tensile and compressive stresses during deformation. Low-frequency piezoelectric ultrasound waves are too long, and the backing layer after use can effectively absorb the sound waves to increase bandwidth, thereby improving axial resolution and imaging quality. A rigid-flexible double-backed composite lining is designed to expand bandwidth while maintaining mechanical flexibility, resulting in a high bandwidth of -6dB to 78% and a low crosstalk of -50dB.

[0022] 2. When the push rod is not in use, the flexible transducer adheres closely to the square structure, providing sufficient mechanical support for abdominal examinations. When the circular push rod is extended, it pushes the flexible transducer into a uniform circular shape, transforming it into a convex array structure to dynamically expand the imaging field of view. This achieves excellent imaging results in dynamic wide-field abdominal imaging, providing strong support for clinical diagnosis.

[0023] 3. The probe achieves dynamic variable curvature imaging through a 3D-printed device, expanding the imaging field of view and meeting the clinical needs of abdominal ultrasound imaging. Combining a flexible convex phased array probe with a Vantage multi-channel signal acquisition system, it achieves high-resolution, high-sensitivity imaging with excellent bending performance. With an appropriate imaging field of view and a large imaging depth, it is suitable for imaging major abdominal organs in various body types.

[0024] 4. Use 3D-printed variable curvature devices to improve reliability, and modulate the two-component viscoelastic substrate to change the tensile stress and compressive stress generated during deformation.

[0025] 5. The effective double-layer composite backing perfectly matches the acoustic impedance of the skin's outer interface, effectively improving acoustic wave transmission efficiency and allowing more sound waves to penetrate the human skin, thereby enhancing imaging quality. Using E-solder material to cast a 0.4mm thick conductive backing with a groove in the azimuth direction not only effectively reduces ringing effects and increases bandwidth, but also enables conformal contact between the OSS shape sensing fiber and any array element, improving spatial positioning accuracy.

[0026] 6. Using a double-cut process to separate the 128 array elements, the two-component substrate is filled in a 7:3 ratio. This not only achieves satisfactory acoustic attenuation and reduces crosstalk between elements, but also provides reliable mechanical support for the second cut to fully separate the elements. Filling with elastic glue ensures effective resilience after bending.

[0027] 7. The backing layer provides sufficient acoustic wave attenuation, shortens the vibration length, increases bandwidth, and suppresses ringing effects to broaden the bandwidth. The backing layer is coupled to the piezoelectric array elements, providing sufficient mechanical support for FPAP bioimaging of arbitrary curvatures and ensuring conformal contact during array bending detection. Double rows of perforations are punched into the PET film and integrated into a 3D-printed variable curvature push rod. The push rod and retracting mechanical claws can change the curvature of the soft probe, effectively expanding the imaging field of view from 90 degrees to 180 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the internal structure of the flexible variable curvature phased array probe based on 3D printing;

[0029] Figure 2 is the bending stress diagram for different curvatures;

[0030] 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°.

[0031] Figure 3 Acquire pattern resolution and contrast images for flexible variable curvature probes;

[0032] Figure 4 Comparison of abdominal renal imaging using a flexible variable curvature probe and a commercial convex array probe;

[0033] Figure 5 Schematic diagram of the three-dimensional structure of the variable curvature putter;

[0034] Figure 6 This is a reference diagram of the state when the circular pushing part of the variable curvature push rod is ejected;

[0035] Figure 7 This is a reference diagram of the state when the circular pushing portion of the variable curvature push rod is contracted;

[0036] 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

[0037] The preferred embodiments of the present invention are described below with reference to 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

[0038] This example discloses a flexible variable curvature phased array probe based on 3D printing and its preparation method, see Figures 1 to 7 A method for preparing a flexible variable curvature phased array probe based on 3D printing comprises the following steps:

[0039] (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 technique to prepare the 1-3 type piezoelectric composite material 12 to form the piezoelectric layer; c. Fill the piezoelectric layer with resin, and the piezoelectric layer includes several array elements;

[0040] (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 for direct contact with the skin;

[0041] (3) The probe has a variable curvature. The array elements described in step (1) are separated using a 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 a sawtooth to cut the piezoelectric layer array elements at equal intervals on the array element matching surface. Fill the cut with a 6:4 viscoelastic composite substrate to prevent adjacent array elements from debonding when the array is bent and 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. Fill the cut with a 5:5 viscoelastic composite substrate with a high elastic modulus so that the bottom of the array element can fully rebound after bending.

[0042] (4) 3D printed flexible printed circuit board 15: A flexible printed circuit board 15 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 a 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retraction of the mechanical claw.

[0043] (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 corresponding electrode of the flexible circuit board; stimulating 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.

[0044] In step (1), the PZT-5H lead zirconate titanate material is 3203HD.

[0045] In step (1), the array element width is 75 μm, and the distance between adjacent array elements is 24 μm.

[0046] 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 polished on both sides to a thickness of 0.6 mm.

[0047] The number of array elements in step (1) is 128.

[0048] In step (2), the thickness of the rigid backing layer is 275 μm, and the thickness of the flexible backing layer is 200 μm.

[0049] Between step (2) and step (3), the process also includes casting a 0.4 mm thick 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.

[0050] In step (3), the array elements are cut at equal intervals using saw teeth. After cutting, the array element width is 0.36 mm and the depth is 0.6 mm.

[0051] The particle size of the aluminum oxide mixture in step (4) is 6 μm; the thickness of the PET film is 0.8 mm.

[0052] A flexible variable curvature phased array probe based on 3D printing is made 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 the piezoelectric layer array element, a flexible printed circuit board is installed in the flexible backing layer 11, a PET film 10 is packaged on the outside of 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, and 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 the cylindrical pushing portion 5 at one end away from the flexible printed circuit board. The two ends of the cylindrical pushing portion 5 are connected to the rope fixing member 7 via a rope 6. The two ends of the rope 6 are fixedly installed at the two ends of the flexible printed circuit board 2. The electrodes of the flexible printed circuit board 2 are connected to the 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.

[0053] A 3MHz, 128-element flexible variable curvature phased array probe (FPAP) fabricated using 3D printing technology is used for dynamic widefield imaging of the abdomen. This flexible probe utilizes a push-pull mechanism to achieve variable curvature deformation and imaging functionality, transforming the imaging field of view from a linear array to a convex array at the flexible probe tip, dynamically expanding the imaging field of view. The thick low-frequency piezoelectric stack is innovatively split using a double-cut process to create a 0.7λ pitch phased array. A prefabricated two-component viscoelastic backing is used for the first time to generate tensile and compressive stresses during deformation. Because low-frequency piezoelectric ultrasound waves are long, the backing layer effectively absorbs the sound waves and increases bandwidth, thereby improving axial resolution and imaging quality. Our innovative design of a rigid-flexible dual-backing composite backing layer achieves wide bandwidth while maintaining mechanical flexibility. This results in a high bandwidth of -6dB to 78% and a low crosstalk of -50dB.

[0054] Structural Innovation: We designed a 3D-printed push-pull mechanism consisting of a circular, retractable push rod, a square structure, and a pull cord. When the push rod is not in use, the flexible transducer adheres closely to the square structure, providing sufficient mechanical support for abdominal examinations. When the circular push rod is extended, it pushes the flexible transducer into a uniform circular shape, forming a convex array structure to dynamically expand the imaging field of view.

[0055] 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 range is 0°~120°. The axial and lateral resolutions of the near-field (30mm), focus (50) and far-field (80mm) line target imaging of the commercial phantom were 0.34mm and 0.36mm, 0.34mm and 0.55mm, 0.35mm and 0.77mm respectively. Finally, 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.

[0056] To solve the problem that traditional rigid transducers have a fixed imaging perspective due to their fixed shape and size during manufacturing, a flexible variable curvature phased array probe is prepared to effectively solve the perspective problem and significantly improve the application effect in human kidney imaging.

[0057] The 3MHz, 128-element flexible variable curvature phased array probe utilizes a 3D-printed device to achieve dynamic variable curvature imaging, expanding the imaging field of view and meeting the clinical needs of abdominal ultrasound imaging. Combining a flexible convex array phased array probe with a Vantage multi-channel signal acquisition system, it achieves high-resolution, high-sensitivity imaging with excellent bending performance. With an appropriate imaging field of view and a large imaging depth, it is suitable for all major abdominal organs in varying body weights.

[0058] The flexible variable-curvature phased array probe consists of three modules: a piezoelectric stack, a rigid-flexible dual backing layer, and a 3D-printed device. The rigid-flexible dual backing layer consists of an E-solder rigid backing and a self-developed high-attenuation composite flexible backing layer. During the fabrication process, a dice-filling technique is used to create a high-performance 1-3 piezoelectric composite material, and an aligned double-cutting process is used to separate the array elements and the rigid backing layer. Furthermore, a 3D-printed variable curvature device provides mechanical reliability and a modulated two-component viscoelastic substrate is used to address the tensile and compressive stresses generated during deformation. Finally, it was determined that the mechanical deformation of the FPAP meets the minimum conformal curvature radius of 12 mm and the curvature range of the variable imaging field of view from 0° to 120°. Piezoelectric Layer Fabrication: The piezoelectric layer uses PZT-5H lead zirconate titanate (3203HD) material. A 1-3 piezoelectric composite material is fabricated using the dice-fill technique. The array element width is 75μm, the kerf is 24μm, and the layer is filled with resin (Epo-Tek 301) and then double-sided polished to a thickness of 0.6mm. The resulting structure achieves a high volume fraction of 57.8% and a thickness-to-width ratio of 8 (0.6 / 0.075mm). This structure effectively reduces acoustic impedance, but still struggles to match the human body's 1.5 Mrayl impedance. According to the KLM equivalent circuit model, an effective matching layer achieves perfect acoustic impedance matching with the skin's external interface, effectively improving acoustic wave transmission efficiency and allowing more sound waves to penetrate the skin, enhancing imaging quality. This flexible variable-curvature phased array probe utilizes a dual-layer composite backing design. The first layer, a 275μm thick conductive matching layer made of epoxy-alumina, is used for matching, while the second layer, which directly contacts the skin, is made of pure epoxy resin and has a thickness of 200μm. Furthermore, a 0.4mm thick conductive backing is cast using E-solder material and features a groove in the azimuth direction. This not only effectively reduces ringing effects and improves bandwidth, but also enables conformal contact between the OSS shape sensing fiber and any array element, enhancing spatial positioning accuracy.

[0059] FPAP's variable curvature implementation process uses a double-cut process to separate 128 array elements, which are then filled with a two-component substrate in a 7:3 ratio. This not only achieves satisfactory acoustic attenuation and reduces crosstalk between elements, but also provides reliable mechanical support for the second cut to fully separate the elements. A 0.3mm sawtooth is used for equidistant cuts at a 0.36 pitch and a depth of 0.6mm. A viscoelastic composite substrate with excellent adhesion prevents debonding between adjacent elements and performs the initial filling. Next, the backing surface is separated by a double-cut process to separate the individual elements and filled with an elastic adhesive, ensuring effective resilience after bending. Finally, an E-solder cut is made at a depth of 0.4mm along the azimuth direction to a depth of 0.25mm, providing a compatible platform for the optical fiber. This process provides excellent mechanical support and acoustic optimization for flexible convex arrays.

[0060] Rigid-flexible dual backing layer and 3D-printed device: The complete backing layer is cast onto a flexible circuit board (FPC) using a mixture of PDMS and 6μm-particle alumina and encapsulated with 0.8mm PET. This provides sufficient acoustic wave attenuation, shortens the vibration length, and increases bandwidth. The entire flexible backing layer has a thickness of 4mm, providing sufficient acoustic attenuation, suppressing ringing effects, and widening the bandwidth. Coupling the backing layer with the 3D-printed piezoelectric array elements provides sufficient mechanical support for FPAP bioimaging of arbitrary curvatures, ensuring conformal contact during array bending detection. Furthermore, double rows of perforations are punched into the PET film and integrated into a 3D-printed variable curvature actuator. The curvature of the soft probe can be varied by pushing and retracting the mechanical gripper, effectively expanding the imaging field of view from 90 degrees to 180 degrees.

[0061] The flexible variable curvature phased array probe enables variable curvature deformation and imaging from a linear array to a convex array, dynamically expanding the imaging field of view. Using a double-cut process to segment the array elements, the probe achieves a 0.7λ pitch phased array. A prefabricated two-component viscoelastic backing layer mitigates tensile and compressive stresses during deformation. An innovative rigid-flexible dual backing layer ensures mechanical flexibility while extending bandwidth from -6dB to 78% and achieving low crosstalk of -50dB. A 3D-printed variable curvature mechanism provides reliable mechanical support. Results show that the FPAP's excellent mechanical deformation meets a conformal minimum curvature radius of 12mm, resulting in a variable curvature range of 0° to 120°. Using a commercial phantom to image a linear target, axial and lateral resolutions of 3mm and 4.2mm were achieved, respectively. Its expandable imaging field of view improves the quality and accuracy of ultrasound imaging, helping physicians better detect pathological tissue or organ behavior.

[0062] Working mode of flexible variable curvature phased array probe:

[0063] The bottom electrodes of each column of piezoelectric array elements are connected one-to-one with the electrodes of the FPC flexible circuit board, so that the electrodes of each column of piezoelectric array elements are electrically conductive with the array on the FPC board; by stimulating the FPC flexible circuit board, all piezoelectric array elements can be stimulated to make them work.

[0064] The flexible array element is precisely positioned using shape-sensing optical fibers. Using an E-solder to cut a 0.25mm depth in the azimuth direction provides a compatible platform for the fiber. By building a system to analyze the fiber and accurately locate ground errors, the quality and accuracy of ultrasound imaging can be further improved.

[0065] Although some preferred embodiments of the present invention have been described, those skilled in the art may make additional 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.

[0066] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

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 technique 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 several array elements; (2) Preparation of a double-layer composite backing: a. Preparation of a rigid backing layer: using epoxy resin and aluminum oxide to prepare a rigid backing layer; b. Preparation of 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 divided using a double-cutting process. The elastic sealant and the one-component room temperature vulcanized silicone rubber sealant are mixed into two different composite two-component bases in a ratio of 6:4 and 5:5 respectively; the elastic sealant is Eeo-flex, and the one-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 base to fill the cut to prevent adjacent array elements from debonding when the array is bent and provide mechanical support for the second complete cutting; b. Secondary alignment cutting and filling: Use an alignment cutting process to completely divide the independent array elements on the backing surface of the array element. Use a 5:5 viscoelastic composite base with a high elastic modulus to fill the cut 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 a 3D printed variable curvature push rod. The curvature of the soft probe is changed by the push rod and the retraction of the 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; 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; and after filling the resin in step c, a double-sided polishing step is also included, in which the lead zirconate titanate filled with the resin is polished on both sides 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, wherein: 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, wherein: 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 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.

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

9. The method for preparing a flexible variable curvature phased array probe based on 3D printing according to claim 1, wherein: 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, manufactured by the method for manufacturing 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 elements, wherein a flexible printed circuit board is installed in the flexible backing layer, wherein a PET film is encapsulated on the outside of the flexible printed circuit board, and a double row of alignment holes is punched on the PET film, and 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 pushing portion capable of pushing the middle part of the flexible printed circuit board to form a convex array structure to achieve dynamic expansion of the imaging field of view, wherein the circular pushing portion is installed in a square structure, wherein the circular pushing portion is connected to a cylindrical pushing portion at one end away from the flexible printed circuit board, and the two ends of the cylindrical pushing portion are connected to a pull rope fixing member via a pull rope, and the two ends of the pull rope are fixedly installed on the two ends of the flexible printed circuit board, the electrodes of the flexible printed circuit board are connected to the piezoelectric layer array elements, and the array elements are 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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