A high-density piezoelectric array flexible film sensor and its acoustic-assisted 3D manufacturing method

Abstract

The present invention discloses a high-density piezoelectric array flexible thin film sensor and its acoustic-assisted 3D manufacturing method. This sensor includes an upper electrode layer, a sensing layer, and a lower electrode layer; the upper electrode layer and the sensing layer are provided with mutually cooperating concave-convex interlocking positioning structures, the upper electrode layer and the lower electrode layer are provided with an upper layer of microparticle silver electrode array and a lower layer of microparticle silver electrode array, respectively, and the sensing layer is provided with a barium titanate microparticle strip array, and the upper layer of microparticle silver electrode array is electrically connected to the lower layer of microparticle silver electrode array via the barium titanate microparticle strip array; this sensor is prepared by an acoustic-assisted 3D printing manufacturing method. The method of the present invention realizes the additive manufacturing of a high-resolution flexible pressure film sensor of 254DPI, solves the problem of low density of traditional piezoelectric film arrays, improves pressure sensing performance and detection resolution, and enhances the flexibility and adherence of the piezoelectric film.

Description

Technical Field

[0001] The present invention relates to the field of flexible piezoelectric sensors, and in particular to a high-resolution micro-convex platform piezoelectric array flexible thin film sensor and a manufacturing method thereof. Background Art

[0002] With the rapid development of smart devices and high-precision sensing technology, the demand for flexible pressure sensors is growing, especially in the fields of wearable devices, robotics, and medical monitoring. Flexible pressure sensors are playing an increasingly important role in modern technology products due to their lightweight and bendable properties, which allow them to adapt to various curved surfaces and dynamic environments.

[0003] Conventional flexible pressure sensors based on piezoelectric microparticle materials often face several technical challenges that restrict their performance and application. Chief among these are the density and resolution limitations of piezoelectric film arrays. Due to the limitations of conventional manufacturing techniques, piezoelectric film arrays often cannot be arranged at high densities within a small space, limiting the sensitivity and accuracy of the sensor. Furthermore, conventional methods often encounter uneven material distribution and difficulty in structural positioning when manufacturing flexible pressure sensors, further impacting the sensor's performance and reliability. Summary of the Invention

[0004] To address the challenges presented in the prior art, the present invention provides a high-density piezoelectric array flexible thin-film sensor and its acoustically assisted 3D manufacturing method. This flexible thin-film sensor, fabricated using surface acoustic wave-assisted photocuring 3D printing technology, boasts high resolution and sensitivity, along with uniform material distribution and structural positioning, significantly improving overall performance and reliability.

[0005] The technical solution adopted in the present invention is as follows:

[0006] (1) A high-density piezoelectric array flexible film sensor

[0007] The flexible thin film sensor is a flexible thin film pressure sensor comprising an upper electrode layer, a sensing layer, and a lower electrode layer stacked in sequence from top to bottom. The upper electrode layer and the sensing layer are provided with interlocking concave and convex positioning structures that cooperate with each other. The lower surface of the upper electrode layer and the upper surface of the lower electrode layer are provided with an upper silver microparticle electrode array and a lower silver microparticle electrode array, respectively. The horizontal projections of the upper and lower silver microparticle electrode arrays overlap. The sensing layer is provided with a barium titanate microparticle strip array, and the upper silver microparticle electrode array is electrically connected to the lower silver microparticle electrode array via the barium titanate microparticle strip array. The edges of the upper electrode layer are bonded to the edges of the lower electrode layer.

[0008] Each upper-layer microparticle silver electrode strip in the upper-layer microparticle silver electrode array and each lower-layer microparticle silver electrode strip in the lower-layer microparticle silver electrode array are formed by aggregation of silver nanoparticles, i.e., by acoustically assisted aggregation of silver nanoparticles suspended in a photosensitive resin. Each barium titanate microparticle strip in the barium titanate microparticle strip array are formed by aggregation of barium titanate nanoparticles, i.e., by acoustically assisted aggregation of barium titanate nanoparticles suspended in a photosensitive resin.

[0009] Specifically, the upper electrode layer includes an upper electrode layer film, a strip boss array, and an upper layer of microparticle silver electrode array, which are sequentially connected from top to bottom. The strip boss array includes a plurality of strip bosses, with the length direction of the strip bosses being the column direction and the direction perpendicular to the column direction being the row direction. The strip bosses are arranged side by side at equal intervals in the row direction, and a groove is formed between two adjacent strip bosses. The upper layer of microparticle silver electrode array includes a plurality of upper layer of microparticle silver electrode strips, with at least one upper layer of microparticle silver electrode strip provided on the lower surface of each strip boss, and at least one upper layer of microparticle silver electrode strip provided on the inner wall surface of the bottom of each groove. Each upper layer of microparticle silver electrode strip extends along the column direction, and the two ends of each upper layer of microparticle silver electrode strip respectively penetrate the two opposite side surfaces of the upper electrode layer in the column direction and are then conductively connected to the outside.

[0010] Preferably, each upper-layer microparticle silver electrode strip is embedded in the lower surface of the strip boss or the inner wall surface of the bottom of the groove, and is exposed on the lower surface of the strip boss or the inner wall surface of the bottom of the groove, so that the upper-layer microparticle silver electrode array can be conductively connected to the lower-layer microparticle silver electrode array of the lower electrode layer through the barium titanate microparticle strip array of the sensing layer.

[0011] Specifically, the lower electrode layer includes a lower electrode film and a lower silver electrode array. The upper and lower surfaces of the lower electrode film are both flat. The lower silver electrode array is provided on the upper surface of the lower electrode film. The lower silver electrode array is primarily formed by a plurality of lower silver electrode strips arranged side by side at equal intervals. Each lower silver electrode strip extends in a column direction, and the two ends of each lower silver electrode strip extend through two opposite side surfaces of the lower electrode layer in the column direction and are then electrically connected to the outside. Each lower silver electrode strip is embedded in the upper surface of the lower electrode film and exposed on the upper surface of the lower electrode film, enabling the lower silver electrode array to be electrically connected to the upper silver electrode strips of the upper electrode layer through the barium titanate strip array of the sensing layer.

[0012] For the upper microparticle silver electrode array of the upper electrode layer and the lower microparticle silver electrode array of the lower electrode layer: the number and arrangement of the lower microparticle silver electrode strips are identical to those of the upper microparticle silver electrode strips, and they are vertically aligned one-to-one; each lower microparticle silver electrode strip is electrically connected to the corresponding upper microparticle silver electrode strip. The upper and lower microparticle silver electrode arrays are formed by acoustically assisted agglomeration of silver nanoparticles suspended in a photosensitive resin solution, which are then coated separately through a photocuring process. This allows the microparticle strips to be deposited on the lower surface of the strip-shaped bosses, the inner wall of the groove bottom, or the upper surface of the lower electrode film, achieving the integrated preparation and tight integration of the microparticle strip electrodes and the photocuring structure.

[0013] The sensing layer is mainly composed of a number of wide-range pressure sensing unit arrays, a number of sensitive pressure sensing unit arrays, and a number of connecting unit arrays, which are periodically and closely arranged. In the row direction, the wide-range pressure sensing unit arrays and the sensitive pressure sensing unit arrays are alternately and evenly arranged side by side, and the wide-range pressure sensing unit arrays are connected to adjacent sensitive pressure sensing unit arrays via connecting unit arrays. The wide-range pressure sensing unit arrays have the same number and arrangement position distribution as the strip-shaped bosses, and are vertically aligned and in contact with each other. The sensitive pressure sensing unit arrays have the same number and arrangement position distribution as the grooves, and are vertically aligned and in contact with each other.

[0014] Each wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array / connection unit linear array is mainly formed by a plurality of wide-range pressure sensing units / sensitive pressure sensing units / connection units arranged evenly at intervals along the column direction, and a barium titanate particle strip is vertically arranged inside each wide-range pressure sensing unit / sensitive pressure sensing unit, and the upper end surface and lower end surface of the barium titanate particle strip are respectively electrically connected to an upper-layer particle silver electrode strip located directly above the barium titanate particle strip and a lower-layer particle silver electrode strip located directly below the barium titanate particle strip.

[0015] Specifically, for the strip-shaped bosses, wide-range pressure sensing unit arrays, and lower-layer micro-particle silver electrode strips aligned in each vertical direction: the upper-layer micro-particle silver electrode strips on the surface of the strip-shaped bosses are electrically connected to the lower-layer micro-particle silver electrode strips via the barium titanate micro-particle strips inside each wide-range pressure sensing unit. For the grooves, sensitive pressure sensing unit arrays, and lower-layer micro-particle silver electrode strips aligned in each vertical direction: the top of each sensitive pressure sensing unit in the sensitive pressure sensing unit array extends into the groove, and the width of the sensitive pressure sensing unit in the row direction matches the width of the groove in the row direction. The upper and lower surfaces of each sensitive pressure sensing unit are in contact with the inner wall of the groove bottom and the upper surface of the lower electrode layer, respectively. The upper-layer micro-particle silver electrode strips on the grooves are electrically connected to the lower-layer micro-particle silver electrode strips via the barium titanate micro-particle strips inside each sensitive pressure sensing unit.

[0016] The lower surface of the sensing layer is flat, meaning the lower surfaces of all wide-range pressure sensing units, connecting units, and sensitive pressure sensing units are aligned horizontally. The thickness of the wide-range pressure sensing units is the same as that of the connecting units, and both are thinner than that of the sensitive pressure sensing units.

[0017] Preferably, the wide-range pressure sensing units, connecting units and sensitive pressure sensing units are all in the shape of cubes; in the row direction, the wide-range pressure sensing units in each wide-range pressure sensing unit array are aligned one by one with the sensitive pressure sensing units in each sensitive pressure sensing unit array.

[0018] Furthermore, each wide-range pressure sensing unit / sensitive pressure sensing unit is mainly composed of a pre-printed layer and a microparticle strip layer, which are arranged in sequence and closely together along the row direction, and barium titanate microparticle strips are provided in the microparticle strip layer.

[0019] (2) A method for acoustically assisted 3D manufacturing of high-density piezoelectric array flexible thin film sensors

[0020] Specifically, an acoustically assisted 3D printing device is used to print the upper electrode layer, the sensing layer, and the lower electrode layer layer by layer according to the following steps to obtain a printed upper electrode layer, a printed sensing layer, and a printed lower electrode layer. After stacking the printed lower electrode layer, the printed sensing layer, and the printed upper electrode layer from bottom to top, the outer edges of the printed upper electrode layer and the printed lower electrode layer are bonded to obtain the flexible thin film sensor.

[0021] The layer-by-layer printing process includes the following steps:

[0022] 1) preparing a nanoparticle-photosensitive prepolymer mixed solution corresponding to the component to be printed and adding it to a printing liquid tank; the component to be printed is an upper electrode layer, a sensing layer, or a lower electrode layer;

[0023] 2) uniformly or non-uniformly dividing the target three-dimensional structure of the component to be printed to obtain a plurality of printing layers and acquiring information of each printing layer;

[0024] The information includes thickness and photocuring pattern. If the printed layer has a particle stripe array, the information also includes particle stripe arrangement parameters, which include particle stripe position, particle stripe spacing, and particle stripe width.

[0025] 3) In the nanoparticle-photosensitive prepolymer mixed solution, adjusting the heights of the carrier platform and the surface acoustic wave excitation platform according to the thickness of the first printed layer, forming an open space between the carrier platform and the surface acoustic wave excitation platform, wherein the initial height of the open space is equal to the thickness of the first printed layer, and the nanoparticle-photosensitive prepolymer mixed solution flows into and fills the open space;

[0026] Take the first printing layer as the current printing layer and proceed to the next step;

[0027] 4) If the information of the current printing layer includes the particle stripe arrangement parameters, proceed to step 5); otherwise, proceed to step 7);

[0028] 5) turning on two interdigital transducers arranged opposite to each other on the surface acoustic wave excitation platform, and simultaneously configuring the output phases of the two interdigital transducers according to the positions of the particle stripes of the current printing layer, so that the acoustic radiation nodes correspond to the positions of the particle stripes one by one, and simultaneously configuring the surface acoustic wave wavelengths of the two interdigital transducers according to the spacing of the particle stripes of the current printing layer, so that the surface acoustic wave wavelength is twice the spacing of the particle stripes, and simultaneously configuring the acoustic radiation forces of the two interdigital transducers according to the width of the particle stripes of the current printing layer, wherein the acoustic radiation force is positively correlated with the width of the particle stripes, a lithium niobate piezoelectric chip is provided in the center of the surface acoustic wave excitation platform, and the two interdigital transducers respectively excite two columns of surface acoustic waves propagating along the surface of the lithium niobate piezoelectric chip, forming a surface acoustic wave pressure field in the open space; the surface acoustic wave pressure field drives the nanoparticles in the nanoparticle-photosensitive prepolymer mixed solution to gather at each acoustic radiation node to form a nanoparticle strip, and the nanoparticle strips at all the acoustic radiation nodes form a nanoparticle strip array; turning off the interdigital transducers;

[0029] 6) Turning on the UV DLP projector, which is inverted and positioned directly above the printing liquid tank, to emit UV light downwardly, the photosensitive prepolymer in the UV light-irradiated area solidifies and covers the nanoparticle strip array formed in step 5), forming a photocured layer having the thickness of the current printing layer, the photocured pattern, and the nanoparticle strip array, and then proceeding to step 8);

[0030] 7) Turning on the UV DLP projector, the UV DLP projector emits UV light downward, and the photosensitive prepolymer in the UV light-irradiated area is cured to form a photocured layer having the thickness of the current printing layer and the photocured pattern, and then proceeding to step 8);

[0031] 8) Control the loading platform to move downward, the moving distance is equal to the thickness of the next printing layer, and the next printing layer is used as the current printing layer;

[0032] 9) Repeating steps 4) to 8) above the lower surface of the loading platform, sequentially forming photocured layers corresponding to each printed layer from bottom to top, until printing is completed, to obtain a printed component;

[0033] 10) Post-processing the printed component to obtain a printed component.

[0034] During the layer-by-layer printing of the top electrode layer using an acoustically assisted 3D printing device: in step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 0.5-20 wt% silver nanoparticles; the specific concentration of the functional medium particles is determined by the desired piezoelectric effect and printing accuracy requirements; in this patent, 5 wt% is used. In step 2), the top electrode layer is vertically divided into two printed layers, one corresponding to the top electrode layer thin film and the other corresponding to the striped boss array, with the layer corresponding to the striped boss array being the first printed layer. In step 10), the printed top electrode layer is post-processed by washing the printed top electrode layer with alcohol, then irradiating it with a UV light source for a period of time to cure the photosensitive resin and ensure that all layers are firmly connected. Finally, a low-power laser is used to etch the bottom surface of the top electrode layer, exposing the first and second top layer silver microparticle electrode strips to the bottom surface of the top electrode layer for external connection.

[0035] During the layer-by-layer printing of the sensing layer using an acoustically assisted 3D printing device: in step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5wt% barium titanate piezoelectric nanoparticles; in step 2), the sensing layer is divided into several printed layers in the row direction, with each wide-range pressure sensing unit array / sensitive pressure sensing unit array being divided into two printed layers, corresponding to the pre-printed layer and the particle strip layer, the pre-printed layer being formed before the particle strip layer; and the structural unit array is divided into one printed layer. In step 10), the printed sensing layer is post-processed as follows: the printed sensing layer is cleaned with alcohol and then irradiated with a UV light source for a period of time to cure the photosensitive resin and ensure that all layers are firmly connected; finally, the upper and lower surfaces of the sensing layer are etched using a low-power laser, so that the ends of the barium titanate particle strips are fully exposed on the upper and lower surfaces of the sensing layer to facilitate external connection.

[0036] In the process of printing the lower electrode layer layer by layer using an acoustic-assisted 3D printing device: in the step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5wt% silver nanoparticles; the step 2) is specifically as follows: first, the lower electrode layer is divided into two printing layers, the thickness of the first printing layer is the thickness of the lower electrode layer, and the thickness of the second printing layer is zero; then, the lower layer microparticle silver electrode array is split into two double-spacing distribution sub-patterns, and the particle strip spacing of the two double-spacing distribution sub-patterns is twice the particle strip spacing of the lower layer microparticle silver electrode array; finally, the horizontal projection pattern of the lower electrode film is split into two strip array patterns, the two strip array patterns correspond one-to-one to the two double-spacing distribution sub-patterns, the bar pattern in each strip array pattern is aligned one-to-one with the particle strip in the corresponding double-spacing distribution sub-pattern, and the width of the strip pattern is greater than the width of the particle strip; the information of the two printing layers respectively includes two double-spacing distribution sub-patterns and the corresponding strip array pattern. In step 10), the process of post-processing the printed lower electrode layer is as follows: using alcohol to clean the printed lower electrode layer, and then irradiating it with a UV light source for a period of time after cleaning to cure the photosensitive resin to ensure that all hierarchical structures are firmly connected; finally, using a low-power laser to etch the upper surface of the lower electrode layer, so that the lower layer of microparticle silver electrode strips are fully exposed on the upper surface of the lower electrode layer to conduct with the outside.

[0037] The conductivity of the silver microparticle electrode strips / barium titanate microparticle strips is related to the degree of aggregation of the silver nanoparticles / barium titanate piezoelectric nanoparticles. During the printing process, the degree of aggregation of the silver microparticle electrode strips can be controlled by adjusting parameters such as the intensity of the surface acoustic wave in the surface acoustic wave pressure field, so that the conductivity and other properties of the silver microparticle electrode strips / barium titanate microparticle strips reach the target value. In the component manufactured using the method of the present invention, the conductivity of the silver microparticle electrode strips can reach about 10 2~10 3 S / m.

[0038] The beneficial effects of the present invention are as follows:

[0039] The flexible thin-film sensor provided by this invention utilizes a concave-convex interlocking structure to securely bond the various material layers, enhancing the sensor's overall stability and compressive resistance. Furthermore, the hollowed-out design within the sensing layer further enhances the sensor's flexibility, making it more suitable for conforming to irregular surfaces and enhancing its potential for application in wearable devices and flexible electronic products.

[0040] 2. The flexible thin film sensor provided by the present invention solves the problems of large spacing between independent particles, poor current conductivity and piezoelectric effect in 3D printing with uniform distribution of traditional particle media through the acoustically assisted arrangement of nanoparticle strips; it solves the shielding effect of high-concentration functional particles on ultraviolet light during ultraviolet light curing in 3D printing, thereby improving the printing effect and quality; the independent piezoelectric strips provide independent voltage signal output, realizing high-resolution piezoelectric sensing performance.

[0041] 3. This invention provides a 3D printing method using surface acoustic wave-assisted photocuring. This method can precisely control the distribution of piezoelectric and conductive materials at the microscale, achieving high-resolution detection of 254 DPI. This precise material control method significantly improves the sensor's sensitivity and pressure detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1. It is a schematic diagram of the layered structure of the sensor of the present invention;

[0043] Figure 2 is a partially enlarged three-dimensional schematic diagram of the upper electrode layer in the sensor of the present invention;

[0044] Figure 3 is a partially enlarged three-dimensional schematic diagram of the sensing layer in the sensor of the present invention;

[0045] Figure 4 is a partially enlarged three-dimensional schematic diagram of the lower electrode layer in the sensor of the present invention;

[0046] Figure 5 Schematic diagram of the concave-convex interlocking positioning structure in the sensor of the present invention;

[0047] Figure 6 Schematic diagram of the acoustic-assisted light-curing 3D printing device in the sensor of the present invention;

[0048] Figure 7 This is a schematic diagram of the printing manufacturing process principle of the sensing layer in the sensor of the present invention;

[0049] Figure 8 It is a schematic diagram of the principle of the printing manufacturing process of the lower electrode layer in the sensor of the present invention.

[0050] In the figure, 1. upper electrode layer; 2. sensing layer; 3. lower electrode layer; 4. first upper layer of microparticle silver electrode strip; 5. strip boss; 6. second upper layer of microparticle silver electrode strip; 7. wide-range pressure sensing unit; 8. connecting unit; 9. sensitive pressure sensing unit; 10. lower layer of microparticle silver electrode strip; 11. lower electrode film; 12. pre-printed layer; 13. barium titanate microparticle strip; 14. lithium niobate piezoelectric chip; 15. interdigital transducer; 16. surface acoustic wave pressure field; 17. loading platform; 18. ultraviolet DLP projection; 19. surface acoustic wave excitation platform; 20. printing liquid tank; 21. Z-axis moving slide; A-A', two ends of the lower layer of microparticle silver electrode strip, B-B', two ends of the lower electrode layer in the direction perpendicular to the lower layer of microparticle silver electrode strip. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, in the present invention, the thin film sensor includes an upper electrode layer 1, a sensing layer 2, and a lower electrode layer 3, which are stacked in sequence from top to bottom. The upper electrode layer 1 and the sensing layer 2 are provided with mutually cooperating concave and convex interlocking positioning structures. The lower surface of the upper electrode layer 1 and the upper surface of the lower electrode layer 3 are provided with an upper layer of microparticle silver electrode array and a lower layer of microparticle silver electrode array, respectively. The upper layer of microparticle silver electrode array and the lower layer of microparticle silver electrode array have the same array distribution, and their projections on the horizontal plane overlap. A barium titanate microparticle strip array is provided within the sensing layer 2. In the barium titanate microparticle strip array, each barium titanate microparticle strip is arranged in a vertical direction and penetrates the upper and lower surfaces of the sensing layer 2. The upper layer of microparticle silver electrode array is electrically connected to the lower layer of microparticle silver electrode array via the barium titanate microparticle strips. The edges of the upper electrode layer 1 are bonded to the edges of the lower electrode layer 3.

[0053] The structure of the upper electrode layer 1 is Figure 2 Display Figure 2The upper electrode layer 1 is inverted, i.e., its original upper surface is facing downward. The upper electrode layer 1 comprises an upper electrode layer film, a strip boss array, and an upper silver microparticle electrode array. The upper surface of the upper electrode layer film is planar and serves as the force-bearing surface of the sensor. The lower surface of the upper electrode layer film is provided with a strip boss array, and the lower surface of the strip boss array is provided with an upper silver microparticle electrode array. The strip boss array comprises a plurality of strip bosses 5 of identical size and shape. The length direction of the upper and lower surfaces of the strip bosses 5 is the column direction, and the direction perpendicular to the column direction is the row direction. The strip bosses 5 are arranged side by side at equal intervals in the row direction, with a groove formed between two adjacent strip bosses 5. The upper-layer microparticle silver electrode array includes several upper-layer microparticle silver electrode strips. At least one upper-layer microparticle silver electrode strip is provided on the lower surface of the strip-shaped boss 5 and the inner wall surface of the groove bottom. Each upper-layer microparticle silver electrode strip extends along the column direction, and its two ends in the column direction respectively penetrate the two opposite side surfaces of the upper electrode layer 1 in the column direction and are then connected to the outside.

[0054] The structure of the lower electrode layer 3 is Figure 4 The lower electrode layer 3 includes a lower electrode film 11 and a lower layer of microparticle silver electrode array. The upper and lower surfaces of the lower electrode film 11 are both flat. The upper surface of the lower electrode film 11 has a lower layer of microparticle silver electrode array. The lower layer of microparticle silver electrode array is mainly formed by a number of lower layer microparticle silver electrode strips 10 arranged side by side at equal intervals. Each lower layer of microparticle silver electrode strip 10 extends along the column direction, and its two ends in the column direction respectively penetrate the two opposite side surfaces of the lower electrode layer 3 in the column direction and are conductive to the outside. The lower layer of microparticle silver electrode strips 10 are the same size, number and arrangement position as the upper layer of microparticle silver electrode strips and are aligned one by one in the vertical direction. Each lower layer of microparticle silver electrode strip 10 is electrically connected to the corresponding upper layer of microparticle silver electrode strip.

[0055] The structure of the sensing layer 2 is Figure 3 The sensing layer 2 is mainly composed of a number of wide-range pressure sensing unit arrays, a number of sensitive pressure sensing unit arrays and a number of connecting unit arrays that are periodically and closely arranged. The periodic and close arrangement specifically means that in the row direction, the wide-range pressure sensing unit arrays and the sensitive pressure sensing unit arrays are alternately and evenly arranged side by side, and the wide-range pressure sensing unit arrays and the adjacent sensitive pressure sensing unit arrays are connected by connecting unit arrays. Figure 5 As shown, the wide-range pressure sensing unit linear array has the same number and arrangement position distribution as the strip bosses 5 and is aligned one by one in the vertical direction and contacts each other, and the sensitive pressure sensing unit linear array has the same number and arrangement position distribution as the grooves and is aligned one by one in the vertical direction and contacts each other.

[0056] Each wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array / connection unit linear array is mainly composed of a number of wide-range pressure sensing units 7 / sensitive pressure sensing units 9 / connection units 8 arranged evenly in the column direction. A barium titanate particle strip 13 is vertically arranged through the interior of each wide-range pressure sensing unit 7, and a barium titanate particle strip 13 is vertically arranged through the interior of each sensitive pressure sensing unit 9. Figure 5 As shown, for the strip bosses 5, the wide-range pressure sensing unit arrays and the lower-layer fine-particle silver electrode strips 10 aligned in each vertical direction, the upper and lower surfaces of each wide-range pressure sensing unit 7 in the wide-range pressure sensing unit array are in contact with the lower surface of the strip bosses 5 and the upper surface of the lower electrode layer 3, respectively, and the upper-layer fine-particle silver electrode strips on the strip bosses 5 are electrically connected to the lower-layer fine-particle silver electrode strips 10 via the barium titanate fine-particle strips 13 inside the wide-range pressure sensing unit 7; Each groove, sensitive pressure sensing unit linear array and lower layer microparticle silver electrode strip 10 are aligned in the vertical direction. The top of each sensitive pressure sensing unit 9 in the sensitive pressure sensing unit linear array is embedded in the groove. The upper and lower surfaces of each sensitive pressure sensing unit 9 are in contact with the inner wall of the groove bottom and the upper surface of the lower electrode layer 3 respectively. The upper layer microparticle silver electrode strip on the groove is electrically connected to the lower layer microparticle silver electrode strip 10 via the barium titanate microparticle strip 13 inside the sensitive pressure sensing unit 9.

[0057] In the above structure, the strip boss array in the upper electrode layer 1 and the wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array in the sensing layer 2 constitute a mutually coordinated concave-convex interlocking positioning structure. This structure firmly combines the materials of each layer, increasing the overall stability and pressure resistance of the sensor.

[0058] The lower surface of the sensing layer 2 is flat, meaning the lower surfaces of all wide-range pressure sensing units 7, connecting units 8, and sensitive pressure sensing units 9 are horizontally aligned. The thickness of the wide-range pressure sensing units 7 is the same as that of the connecting units 8, and both are thinner than that of the sensitive pressure sensing units 9.

[0059] Furthermore, the wide-range pressure sensing unit 7, the connecting unit 8, and the sensitive pressure sensing unit 9 are all in the shape of a cube. In the row direction, the number and arrangement position of the wide-range pressure sensing units 7 and the sensitive pressure sensing units 9 are the same and aligned one by one. One side of the connecting unit 8 is connected to two wide-range pressure sensing units 7 in the adjacent wide-range pressure sensing unit array, and the other side of the connecting unit 8 is connected to two sensitive pressure sensing units 9 in the adjacent sensitive pressure sensing unit array. The hollow structure composed of the wide-range pressure sensing unit 7, the sensitive pressure sensing unit 9, and the connecting unit 8 further improves the flexibility of the sensor, making it more suitable for fitting to irregular surfaces and enhancing its application potential in wearable devices and flexible electronic products.

[0060] Each wide-range pressure sensing unit 7 / sensitive pressure sensing unit 9 is mainly composed of a pre-printed layer 12 and a particle strip layer. The pre-printed layer 12 and the particle strip layer are arranged in sequence along the row direction. The particle strip layer is provided with barium titanate particle strips. The pre-printed layer 12 does not have barium titanate particle strips and is used to encapsulate barium titanate particle strips.

[0061] The upper electrode layer 1, sensing layer 2, and lower electrode layer 3 are all fabricated in an integrated manner using acoustic-assisted 3D printing technology. The sensing layer 2 is made of a photosensitive prepolymer containing 5% barium titanate piezoelectric nanoparticles. Both the upper and lower electrode layers 1 and 3 are made of photosensitive prepolymers containing 5% silver nanoparticles. The size of both the barium titanate and silver nanoparticles ranges from 10 to 10,000 nm. The photosensitive prepolymer is a mixture of polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, and ethyl 2,4,6-trimethylbenzoylphosphinate.

[0062] In the present invention, the manufacturing process of the thin film sensor is: using an acoustically assisted 3D printing device to print the upper electrode layer 1, the sensing layer 2 and the lower electrode layer 3 layer by layer according to the following steps to obtain a printed upper electrode layer 1, a printed sensing layer 2 and a printed lower electrode layer 3; after stacking the printed lower electrode layer 3, the printed sensing layer 2 and the printed upper electrode layer 1 from bottom to top, the outer edges of the printed upper electrode layer 1 and the printed lower electrode layer 3 are bonded to obtain a flexible thin film sensor.

[0063] The layer-by-layer printing process is based on surface acoustic wave-assisted photocuring 3D printing technology. This manufacturing method can precisely control the spatial arrangement and structural curing of materials at a microscopic scale, significantly improving the resolution and sensitivity of the pressure sensor.

[0064] 1) Preparing a nanoparticle-photosensitive prepolymer mixed solution: preparing a nanoparticle-photosensitive prepolymer mixed solution corresponding to the component to be printed, and adding the nanoparticle-photosensitive prepolymer mixed solution into the printing liquid tank 20. The component to be printed is the upper electrode layer 1, the sensing layer 2, or the lower electrode layer 3.

[0065] 2) Obtaining printed layers and printed layer information: A plurality of printed layers are obtained by non-uniformly dividing the target three-dimensional structure of the component to be printed. Information about each printed layer is obtained, including thickness and photocuring pattern. If the printed layer has a particle stripe array, the information also includes particle stripe arrangement parameters, including particle stripe position, particle stripe spacing, and particle stripe width.

[0066] 3) Injecting a nanoparticle-photosensitive prepolymer mixed solution into the open space having an initial height: In the nanoparticle-photosensitive prepolymer mixed solution, the heights of the carrier platform 17 and the surface acoustic wave excitation platform 19 are adjusted according to the thickness of the first printed layer, forming an open space between the carrier platform 17 and the surface acoustic wave excitation platform 19. The initial height of the open space is equal to the thickness of the first printed layer, and the nanoparticle-photosensitive prepolymer mixed solution flows into and fills the open space; the first printed layer is used as the current printed layer and the process proceeds to the next step;

[0067] 4) If the information of the current printing layer includes the particle stripe arrangement parameters, proceeding to step 5) to form the particle stripe array by surface acoustic wave assistance; if the information of the current printing layer does not include the particle stripe arrangement parameters, proceeding to step 7) to directly form a photocured layer having the current printing layer thickness and photocured pattern by photocuring;

[0068] 5) Turn on two interdigital transducers 15 arranged opposite to each other on the surface acoustic wave excitation platform 19, and configure the output phase, surface acoustic wave wavelength, and acoustic radiation force of the two interdigital transducers 15 according to the particle strip position, particle strip spacing, and particle strip width of the current printing layer. A lithium niobate piezoelectric chip 14 is provided in the center of the surface acoustic wave excitation platform 19. The two interdigital transducers 15 respectively excite two columns of surface acoustic waves propagating along the surface of the lithium niobate piezoelectric chip 14. The two columns of surface acoustic waves have the same frequency but propagation directions are opposite. The two columns of surface acoustic waves interfere with each other to form The surface acoustic wave pressure field 16 is generated in the open space; the surface acoustic wave pressure field 16 drives the nanoparticles in the nanoparticle-photosensitive prepolymer mixed solution to move toward the nearby acoustic radiation nodes, and the nanoparticles gather at each acoustic radiation node to form a nanoparticle strip. The nanoparticle strips at all the acoustic radiation nodes form a nanoparticle strip array, and the particle strip spacing and particle strip width of the nanoparticle strip array are the same as the particle strip spacing and particle strip width of the current printing layer; the interdigital transducer 15 is turned off;

[0069] The position of the acoustic radiation node is adjusted by simultaneously controlling the phase of two surface acoustic waves. The acoustic radiation force is positively correlated with the width of the particle stripe. The spacing between the particle stripes is half the wavelength of the surface acoustic wave. This step achieves precise arrangement of piezoelectric material particles such as barium titanate nanoparticles and silver nanoparticles through the surface acoustic wave pressure field 16. This enables more uniform material distribution and structural positioning during the photocuring process through the assistance of acoustic waves, effectively improving the overall performance and reliability of the sensor.

[0070] 6) Turning on the UV DLP projector 18, which is inverted and positioned directly above the printing liquid tank 20, the UV DLP projector 18 emits UV light downwardly and irradiates the nanoparticle-photosensitive prepolymer mixed solution within a preset height range of the imaging surface. The UV light modulates the photocurable pattern of the current printing layer. The photosensitive prepolymer in the UV-irradiated area cures and covers the nanoparticle strip array formed in step 5), forming a photocurable layer having the thickness of the current printing layer, the photocurable pattern, and the nanoparticle strip array, and then proceeding to step 8);

[0071] 7) Turn on the UV DLP projector 18 that is inverted and directly above the printing liquid tank 20. The UV DLP projector 18 emits UV light downward and irradiates the nanoparticle-photosensitive prepolymer mixed solution within a preset height range of the imaging surface. The UV light modulates the photocurable pattern of the current printing layer. The photosensitive prepolymer in the UV light irradiation area is cured to form a photocurable layer having the thickness of the current printing layer and the photocurable pattern, and then proceeds to step 8); the preset height range is positively correlated with the irradiation time of the UV light; by adjusting the vertical position of the imaging surface of the UV DLP projector 18, ensure that the UV light is accurately irradiated to the corresponding height of the current printing layer, and at the same time, by controlling the irradiation time to ensure that the material is cured to an appropriate degree.

[0072] 9) Control the loading platform 17 to move downward by a distance equal to the thickness of the next printing layer, and use the next printing layer as the current printing layer to proceed to the next step;

[0073] 10) Repeating steps 4) to 9) to sequentially form a photocured layer having information of each printing layer on the lower surface of the loading platform 17 from bottom to top until printing is completed, thereby obtaining a printed component;

[0074] 11) Post-processing the printed component to obtain a printed component.

[0075] Furthermore, during the layer-by-layer printing of the upper electrode layer 1 using an acoustically assisted 3D printing device: in step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5 wt% silver nanoparticles. In step 2), the upper electrode layer 1 is vertically divided into two printed layers, corresponding to the upper electrode layer thin film and the striped boss array, respectively. Information on both printed layers includes the particle stripe arrangement parameters. Finally, the printed layer corresponding to the striped boss array is the first printed layer.

[0076] Furthermore, during the layer-by-layer printing of the sensing layer 2 using an acoustically assisted 3D printing device: in step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5wt% barium titanate piezoelectric nanoparticles. In step 2), the sensing layer 2 is divided into several printed layers in the row direction. Each wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array is divided into two printed layers, and the two printed layers correspond to the pre-printed layer 12 and the particle stripe layer. The information of the printed layer corresponding to the pre-printed layer 12 does not include the particle stripe arrangement parameters, while the information of the printed layer corresponding to the particle stripe layer includes the particle stripe arrangement parameters. The printed layer corresponding to the pre-printed layer 12 precedes the printed layer corresponding to the particle stripe layer. The structural unit linear array is divided into one printed layer, and the information of the printed layer corresponding to the structural unit linear array does not include the particle stripe arrangement parameters. In this process, the pre-printed layer 12 is formed by moving the slide slightly and performing pre-curing. The introduction of the pre-printed layer 12 solves the problem of the required arrangement particles being suspended in the air. Under the combined influence of the acoustic radiation force field and the gravity field, the particles aggregate and align above the pre-printed layer 12, forming a particle strip. The particle strip is then covered with a photosensitive prepolymer cured with UV light, ultimately forming the desired structure, such as a linear array of wide-range or sensitive pressure sensing units. During this process, UV light is irradiated from above to form the photocured layer, positioning the particle strip away from the light source. This prevents the particles from strongly shielding against UV light, increases the maximum printable concentration of the functional nanoparticle medium, and enhances the printability of the structure.

[0077] Furthermore, in the process of printing the lower electrode layer 3 layer by layer using the acoustic-assisted 3D printing device: in step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5 wt% of silver nanoparticles. In step 2), first, the lower electrode layer 3 is divided into two printed layers, the thickness of the first printed layer is the thickness of the lower electrode layer 3, and the thickness of the second printed layer is zero; then, the particle stripe array of the lower electrode layer 3 in the horizontal direction is divided into blocks to form two double-spacing distribution sub-patterns, the superposition and intersection of the two double-spacing distribution sub-patterns is the particle stripe array of the lower electrode layer 3, and the particle stripe spacing in the two double-spacing distribution sub-patterns is twice the particle stripe spacing in the particle distribution pattern of the lower electrode layer 3; finally, the photocured pattern of the lower electrode layer 3 is divided into blocks to form two stripe array patterns, and the superposition and intersection of the two stripe array patterns is the photocured pattern of the lower electrode layer 3; the two stripe array patterns correspond one-to-one to the two double-spacing distribution sub-patterns, and each bar pattern in the stripe array pattern is aligned one-to-one with the particle stripe in the corresponding double-spacing distribution sub-pattern; the information of each printed layer includes a double-spacing distribution sub-pattern and a corresponding stripe array pattern.

[0078] During the printing process, the photocured layers corresponding to the two printed layers are both formed on the lower surface of the loading platform 17 , and the two photocured layers are connected and combined to form the printed lower electrode layer 3 .

[0079] The above-mentioned acoustic-assisted 3D printing device includes a printing liquid tank 20, a loading platform 17, a surface acoustic wave excitation platform 19 and an ultraviolet DLP projector 18 arranged in sequence from bottom to top; the loading platform 17 and the surface acoustic wave excitation platform 19 are both capable of reciprocating in the vertical direction, and the projection end of the ultraviolet DLP projector 18 is arranged downward; a lithium niobate piezoelectric chip 14 and several pairs of interdigital transducers 15 are provided on the surface acoustic wave excitation platform 19, the lithium niobate piezoelectric chip 14 is arranged in the middle of the surface acoustic wave excitation platform 19, and the interdigital transducers 15 are arranged around the lithium niobate piezoelectric chip 14; each pair of interdigital transducers 15 includes two oppositely arranged interdigital transducers, and the two interdigital transducers 15 respectively excite two surface acoustic waves, the two surface acoustic waves have the same frequency but opposite propagation directions, the two surface acoustic waves propagate along the surface of the lithium niobate piezoelectric chip 14 and form standing waves through interference, thereby generating a surface acoustic wave pressure sound field 16 between the surface acoustic wave excitation platform 19 and the loading platform 17. The IDT 15 is electrically connected to an external signal generator, which is used to configure the acoustic parameters of the surface acoustic wave.

[0080] The specific embodiments of the present invention are as follows:

[0081] 1. Flexible film pressure sensor

[0082] The following Figures 1 to 5The illustrated embodiment is taken as an example to illustrate the structure and preparation method of the flexible thin film pressure sensor of the piezoelectric high-density array and its working mechanism of the present invention.

[0083] like Figure 1 As shown, the pressure sensor is a 5mm-squared, 400μm-thick cube-shaped thin film containing approximately 1,200 piezoelectric sensing units. The pressure sensor consists of an upper electrode layer 1, a sensing layer 2, and a lower electrode layer 3, stacked in sequence from top to bottom.

[0084] The upper electrode layer 1 includes a strip-shaped boss 5, a first upper layer of microparticle silver electrode strips 4, and a second upper layer of microparticle silver electrode strips 6. The strip-shaped boss 5 is formed by light-curing a photosensitive prepolymer, and the first upper layer of microparticle silver electrode strips 4 and the second upper layer of microparticle silver electrode strips 6 are both formed by acoustically assisted arrangement of silver nanoparticles. The dimensions of the upper electrode layer 1 are: the overall thickness of the upper electrode layer 1 is 150 μm, and the thickness of the upper film is 100 μm; the height of each strip boss 5 is 50 μm, the width is 120 μm, and the length is 5 mm, and the spacing between two adjacent strip bosses 5 is 80 μm; the spacing between two adjacent upper-layer microparticle silver electrode strips (the first upper-layer microparticle silver electrode strip 4 and the second upper-layer microparticle silver electrode strip 6) is 100 μm, and the spacing between the upper-layer microparticle silver electrode strips in a single arrangement (the spacing between two adjacent first upper-layer microparticle silver electrode strips 4, the spacing between two adjacent second upper-layer microparticle silver electrode strips 6) is 200 μm; the width of the upper-layer microparticle silver electrode strips is smaller than the width and spacing of the strip boss 5, that is, there is no conduction between the two.

[0085] The sensing layer 2 includes a wide-range pressure sensing unit 7, a connecting unit 8, and a sensitive pressure sensing unit 9. The dimensions of the sensing layer 2 are as follows: the wide-range pressure sensing unit 7 has a length L1 of 80 μm, a width W1 of 50 μm, and a height H1 of 100 μm; the connecting unit 8 has a length L2 of 60 μm, a width W2 of 50 μm, and a height H3 of 100 μm; and the sensitive pressure sensing unit 9 has a length L3 of 80 μm, a width W3 of 50 μm, and a height H3 of 150 μm.

[0086] Each wide-range pressure sensing unit 7 and each wide-range pressure sensing unit 9 has a barium titanate particle strip 13. By measuring the voltage change across the wide-range pressure sensing unit 7 / sensitive pressure sensing unit 9, the pressure distribution of the sensing unit is measured.

[0087] Wide-range pressure sensing units 7 and 9 are connected by connecting units 8, which are made by light-curing uniformly distributed barium titanate nanoparticles and a photosensitive prepolymer. Specifically, each connecting unit 8 connects to four side pressure sensing units (two wide-range pressure sensing units 7 and two wide-range pressure sensing units 9), forming a stable structure. This creates a hollow structure with uniformly distributed gaps between the pressure sensing units and the connecting structure, reducing the overall weight of the sensor without compromising structural strength and increasing its flexibility.

[0088] The structure of the lower electrode layer 3 is as follows Figure 4 As shown, the main body is a photocurable film, with a lower layer of microparticle silver electrodes arrayed on one side. Each lower layer of microparticle silver electrodes is aligned with a row of barium titanate microparticle strips in the sensing layer 2. The dimensions of the lower electrode layer 3 are: 100μm thick, and the spacing between the lower layer of microparticle silver electrodes is 100μm. The conductivity between A-A' and B-B' was measured, and the conductivity between A-A' was approximately 800S / m, while there was no conductivity between B-B'.

[0089] like Figure 5 As shown, the array of strip-shaped bosses in the upper electrode layer 1 cooperates with the array of pressure cells in the sensing layer 2. Strip-shaped bosses 5 are in contact with wide-range pressure sensing cells 7, while one end of sensitive pressure sensing cell 9 is embedded in the grooves between the strip-shaped bosses 5 and in contact with the bottom of the grooves. This interlocking concave-convex structure strengthens the bond between the upper electrode layer and the pressure sensing layer, ensuring that the relative positions of the layers remain fixed when subjected to external forces, thereby improving the lifespan and reliability of the sensor.

[0090] 2. Sound-assisted 3D printing device

[0091] In this embodiment, an acoustically assisted 3D printing device is used to manufacture the flexible film sensor.

[0092] like Figure 6 As shown, the acoustic-assisted 3D printing device is placed on a vibration isolation platform, and includes an electric Z-axis moving slide 21, an ultraviolet DLP projector 18, a loading platform 17, a surface acoustic wave excitation platform 19, and a printing liquid tank 20.

[0093] The loading platform 17 is fixedly connected to a Z-axis movable slide 21. By moving the Z-axis movable slide 21, the Z-axis position of the loading platform 17 in the printing liquid tank 20 can be controlled. A surface acoustic wave excitation platform 19 is located above the loading platform 17 and can move back and forth in the Z-axis direction. The UV DLP projector 18 is inverted above the surface acoustic wave excitation platform 19. A lithium niobate piezoelectric chip 14 is located in the center of the surface acoustic wave excitation platform 19, directly above the loading platform 17. Several pairs of interdigital transducers 15 are arranged around the lithium niobate piezoelectric chip 14. Each pair of interdigital transducers 15 consists of two opposing interdigital transducers 15, and the interdigital transducers 15 are electrically connected to an external signal generator.

[0094] 3. Surface Acoustic Wave-Assisted Light-Stereolithography 3D Printing Method

[0095] In this embodiment, the upper electrode layer 1, lower electrode layer 3 and sensing layer 2 of the sensor are all manufactured by surface acoustic wave assisted light curing 3D printing method. The manufacturing process of each component is as follows:

[0096] 1) Fabrication of upper electrode layer 1

[0097] Filling the printing liquid tank 20 with a photosensitive prepolymer solution containing silver nanoparticles;

[0098] The carrier platform 17 is moved up and down in the printing liquid tank 20 by the movable slide 21. The distance between the carrier platform 17 and the surface acoustic wave excitation platform 19 is adjusted to 50 μm according to the height of the strip boss 5. An open space is formed between the carrier platform 17 and the surface acoustic wave excitation platform 19, and a photosensitive prepolymer solution containing uniformly distributed silver nanoparticles is allowed to fill the space.

[0099] Two opposing interdigital transducers 15 are used to excite two arrays of surface acoustic waves on the surface of the lithium niobate piezoelectric wafer 14. The two arrays of surface acoustic waves are two traveling waves that superimpose in an open space to form a stable standing wave. The standing wave forms an acoustic radiation force field in the photosensitive prepolymer solution. The silver nanoparticles in the photosensitive prepolymer solution are affected by the acoustic radiation force field and move toward the nearest acoustic radiation node. After the position of the silver nanoparticles in the photosensitive prepolymer solution stabilizes, several first upper-layer microparticle silver electrode strips 4 are formed that run through the solution.

[0100] Turn off the interdigital transducer 15 and turn on the UV DLP projector 18 to solidify the corresponding area according to the projection pattern of the stripe boss array on the horizontal plane. After solidification, a stripe boss array is formed.

[0101] Turn off the UV DLP projector 18, keep the height of the surface acoustic wave excitation platform 19 unchanged, and control the loading platform 17 to move downward by 100 μm according to the thickness of the upper film of the upper electrode layer 1, waiting for the photosensitive prepolymer solution containing uniformly distributed silver nanoparticles to fill into the space;

[0102] The interdigital transducer 15 is turned on, and a plurality of second upper layer microparticle silver electrode strips 6 are formed through the front and back through the surface acoustic wave.

[0103] The interdigital transducer 15 is turned off, and the UV DLP projector 18 is turned on. The corresponding area is cured according to the projection pattern of the upper film on the horizontal plane. The photosensitive prepolymer solution within a certain height range is cured by controlling the exposure time. After the curing is completed, the printed upper electrode layer 1 is obtained;

[0104] The printed upper electrode layer 1 is post-processed: the printed upper electrode layer 1 is cleaned with alcohol and then irradiated with a UV light source for 3 minutes to cure the photosensitive resin to ensure that all hierarchical structures are firmly connected; finally, a low-power laser is used to etch the lower surface of the upper electrode layer 1 so that the silver nanoparticle strips 4 and 6 are fully exposed and conductive.

[0105] After turning on the IDT 15, the phases of the two surface acoustic waves are simultaneously controlled to align the upper silver electrode strips with the center of the strip-shaped boss 5 or the center of the groove. By controlling the voltage amplitude, the acoustic radiation force is varied, thereby regulating the width of the upper silver electrode strips. The acoustic radiation force is positively correlated with the width of the upper silver electrode strips. By adjusting the surface acoustic wave wavelength, the spacing between the upper silver electrode strips is controlled, with the spacing between the upper silver electrode strips being half the surface acoustic wave wavelength.

[0106] 2) Fabrication of sensing layer 2

[0107] In this embodiment, the thickness of the pre-printed layer 12 is 10 μm, and the thickness of the remaining portion is 40 μm.

[0108] like Figure 7 As shown, a two-step method is used to print a wide-range pressure sensing unit array and a sensitive pressure sensing unit array. The two-step printing process includes the following steps:

[0109] According to the height of the pre-printed layer 12, an open space with a height of 10 μm is formed between the carrier platform 17 and the surface acoustic wave excitation platform 19, or the carrier platform 17 is moved downward by 10 μm;

[0110] Turn on the UV DLP projector 18 and solidify the corresponding area according to the pattern of the current printing layer. After solidification is completed, the pre-printed layer 12 is obtained.

[0111] The loading platform 17 is controlled to move downward 40 μm, and the interdigital transducer 15 is turned on to form several front-to-back through-line barium titanate particle strips with the assistance of surface acoustic waves; the interdigital transducer 15 is turned off, and the ultraviolet DLP projector 18 is turned on to cure the corresponding area according to the photocuring pattern of the current printing layer. After curing is completed, a wide-range pressure sensing unit linear array or a sensitive pressure sensing unit linear array is formed.

[0112] In addition, for the connection unit linear array, only two steps are performed: moving the loading platform 17 and turning on the ultraviolet DLP projector 18 for light curing. There is no need to use surface acoustic wave to assist in the arrangement of the barium titanate therein.

[0113] 3) Fabrication of lower electrode layer 3

[0114] In this embodiment, the Figure 8 The single-layer multi-step method shown is used to prepare the lower electrode layer 3. The specific steps are as follows:

[0115] Filling the printing liquid tank 20 with a photosensitive prepolymer solution containing silver nanoparticles;

[0116] The loading platform 17 is controlled to move up and down in the printing liquid tank 20 to form an open space with a height of 100 μm, which is the same as the thickness of the lower electrode layer 3, and wait for the photosensitive prepolymer solution containing uniformly distributed silver nanoparticles to fill into the space;

[0117] like Figure 8 As shown in (a), the interdigital transducer 15 is turned on to excite the surface acoustic wave to arrange the silver nanoparticles in the photosensitive prepolymer. The spacing between the particle stripes is half the wavelength of the surface acoustic wave, about 200 μm.

[0118] like Figure 8 As shown in (b), a DLP photocuring mask is set with the imaging surface above the arrangement position of the silver nanoparticle strips, and the photosensitive prepolymer within a width of 100 μm around each silver nanoparticle strip is cured to obtain a photocured layer;

[0119] like Figure 8 As shown in (c), the photosensitive prepolymer solution containing uniformly distributed silver nanoparticles is refilled into the gaps in the photocurable layer, and the surface acoustic waves are excited again, and the phase is adjusted so that the particles gather between the gaps of the last arrangement, forming silver nanoparticle strips;

[0120] like Figure 8 As shown in (d), the DLP photocuring mask is reset so that the imaging surface is above the position of the second arrangement of the silver nanoparticle strips, and the photosensitive prepolymer within a width of 100 μm around each silver nanoparticle strip formed by the second arrangement is cured to complete the single-layer arrangement.

[0121] After arrangement, the spacing between the silver nanoparticle strips is one-quarter of the wavelength of the surface acoustic wave, about 100 μm.

[0122] Finally, the printed component is cleaned with alcohol and irradiated with a UV light source for 3 minutes to cure the photosensitive resin to ensure that all hierarchical structures are firmly connected; finally, a low-power laser is used to etch the surface so that the underlying micro-silver electrode strips 10 are fully exposed and conductive.

[0123] In summary, the present invention utilizes surface acoustic wave (SAW) technology to precisely control the position and distribution of barium titanate and silver nanoparticles during 3D printing. Through the action of acoustic radiation forces, the particles in the photosensitive prepolymer are precisely assembled at predetermined locations and photocured to form a pressure sensing array and conductive electrode layer with optimized geometry. By designing the thickness distribution of the sensing layer, sensitive pressure sensing units and large-range sensing units are introduced, improving the sensor's range and detection range. A hollowing design within the pressure sensing layer reduces the overall weight of the sensor and increases its flexibility without compromising structural strength. An interlocking structure is employed between the electrode layer and the sensing layer, strengthening the bond between the upper electrode layer and the pressure sensing layer and ensuring the relative position of the layers remains fixed when subjected to external forces, thereby improving the sensor's service life and reliability. Using a SAW-assisted, photocurable 3D printing method, a high resolution of 254 DPI is achieved, effectively addressing the low density and insufficient resolution of conventional piezoelectric film arrays. This technology enables the sensor to detect pressure changes at a finer scale, making it suitable for high-precision pressure measurement.

[0124] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A high-density piezoelectric array flexible thin film sensor, characterized by: The invention comprises an upper electrode layer (1), a sensing layer (2) and a lower electrode layer (3) which are stacked in sequence from top to bottom; the upper electrode layer (1) and the sensing layer (2) are provided with mutually matched concave-convex interlocking positioning structures; the lower surface of the upper electrode layer (1) and the upper surface of the lower electrode layer (3) are provided with an upper layer of microparticle silver electrode array and a lower layer of microparticle silver electrode array respectively; the projections of the upper layer of microparticle silver electrode array and the lower layer of microparticle silver electrode array on the horizontal plane overlap; the sensing layer (2) is provided with a barium titanate microparticle strip array, and the upper layer of microparticle silver electrode array is electrically connected to the lower layer of microparticle silver electrode array via the barium titanate microparticle strip array; Each upper-layer microparticle silver electrode strip in the upper-layer microparticle silver electrode array and each lower-layer microparticle silver electrode strip (10) in the lower-layer microparticle silver electrode array are formed by the aggregation of silver nanoparticles; and each barium titanate microparticle strip in the barium titanate microparticle strip array are formed by the aggregation of barium titanate nanoparticles.

2. The high-density piezoelectric array flexible thin film sensor according to claim 1, characterized in that: The upper electrode layer (1) comprises an upper electrode layer film, a strip boss array and an upper layer microparticle silver electrode array connected in sequence from top to bottom; the strip boss array comprises a plurality of strip bosses (5), with the length direction of the strip bosses (5) being the column direction and the direction perpendicular to the column direction being the row direction, the strip bosses (5) being arranged side by side at equal intervals, and a groove being formed between two adjacent strip bosses (5); at least one upper layer microparticle silver electrode strip is provided on the lower surface of the strip bosses (5) and the inner wall of the bottom of the groove, and each upper layer microparticle silver electrode strip extends along the column direction and has two ends passing through two opposite side surfaces of the upper electrode layer (1).

3. The high-density piezoelectric array flexible thin film sensor according to claim 2, characterized in that: The lower electrode layer (3) includes a lower electrode film (11) and a lower layer of microparticle silver electrode array; the upper and lower surfaces of the lower electrode film (11) are both planes, and the upper surface of the lower electrode film (11) is provided with a lower layer of microparticle silver electrode array, and the lower layer of microparticle silver electrode array is mainly composed of a plurality of lower layer of microparticle silver electrode strips (10) arranged side by side at equal intervals, and the two ends of each lower layer of microparticle silver electrode strip (10) respectively penetrate the two opposite side surfaces of the lower electrode layer (3); the number and arrangement position distribution of the lower layer of microparticle silver electrode strips (10) are the same as those of the upper layer of microparticle silver electrode strips and are aligned one by one in the vertical direction; each lower layer of microparticle silver electrode strip (10) is electrically connected to the corresponding upper layer of microparticle silver electrode strip.

4. The high-density piezoelectric array flexible thin film sensor according to claim 3, characterized in that: The sensing layer (2) is mainly composed of a plurality of wide-range pressure sensing unit arrays, a plurality of sensitive pressure sensing unit arrays and a plurality of connecting unit arrays that are periodically and closely arranged; in the row direction, the wide-range pressure sensing unit arrays and the sensitive pressure sensing unit arrays are alternately and evenly arranged side by side, and the wide-range pressure sensing unit arrays and adjacent sensitive pressure sensing unit arrays are connected via connecting unit arrays; the wide-range pressure sensing unit arrays and the strip-shaped bosses (5) are aligned one by one in the vertical direction and contact each other, and the sensitive pressure sensing unit arrays and the grooves are aligned one by one in the vertical direction and contact each other; Each wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array / connection unit linear array is mainly formed by a plurality of wide-range pressure sensing units (7) / sensitive pressure sensing units (9) / connection units (8) arranged evenly at intervals along the column direction, and a barium titanate particle strip (13) is vertically arranged inside each wide-range pressure sensing unit (7) / sensitive pressure sensing unit (9), and the upper end face and the lower end face of the barium titanate particle strip (13) are electrically connected to the upper particle silver electrode strip and the lower particle silver electrode strip (10) respectively.

5. The high-density piezoelectric array flexible thin film sensor according to claim 4, characterized in that: The wide-range pressure sensing unit (7), the connecting unit (8) and the sensitive pressure sensing unit (9) are all in the shape of a cube; in the row direction, the wide-range pressure sensing unit (7) and the sensitive pressure sensing unit (9) are aligned one by one.

6. The high-density piezoelectric array flexible thin film sensor according to claim 4, characterized in that: Each wide-range pressure sensing unit (7) / sensitive pressure sensing unit (9) is mainly composed of a pre-printed layer (12) and a particle strip layer, wherein the pre-printed layer (12) and the particle strip layer are arranged in sequence along the row direction, and barium titanate particle strips are arranged in the particle strip layer.

7. A method for manufacturing a high-density piezoelectric array flexible thin film sensor by acoustically assisted 3D printing according to any one of claims 1 to 6, characterized in that: According to the following steps, the upper electrode layer (1), the sensing layer (2) and the lower electrode layer (3) are printed layer by layer to obtain a printed upper electrode layer (1), a printed sensing layer (2) and a printed lower electrode layer (3); the printed lower electrode layer (3), the printed sensing layer (2) and the printed upper electrode layer (1) are stacked in sequence from bottom to top; and the outer edges of the printed upper electrode layer (1) and the printed lower electrode layer (3) are bonded to obtain a flexible thin film sensor; The layer-by-layer printing process includes the following steps: 1) preparing a nanoparticle-photosensitive prepolymer mixed solution corresponding to a component to be printed and adding the solution to a printing liquid tank (20); the component to be printed is an upper electrode layer (1), a sensing layer (2) or a lower electrode layer (3); 2) Dividing the target three-dimensional structure of the component to be printed into a plurality of printed layers, and obtaining information of each printed layer; The information includes thickness and photocuring pattern. If the printed layer has a particle stripe array, the information also includes particle stripe arrangement parameters, which include particle stripe position, particle stripe spacing, and particle stripe width. 3) forming an open space between the loading platform (17) and the surface acoustic wave excitation platform (19), wherein the initial height of the open space is equal to the thickness of the first printed layer, and the nanoparticle-photosensitive prepolymer mixed solution flows into and fills the open space; then, the first printed layer is used as the current printing layer, and the next step is entered; 4) If the information of the current printing layer includes the particle stripe arrangement parameters, proceed to step 5); otherwise, proceed to step 7); 5) Turning on two interdigital transducers (15) arranged opposite to each other, configuring the surface acoustic wave wavelengths of the two interdigital transducers (15) according to the position of the particle strips of the current printing layer, configuring the output phases of the two interdigital transducers (15) according to the spacing of the particle strips of the current printing layer, and configuring the acoustic radiation forces of the two interdigital transducers (15) according to the width of the particle strips of the current printing layer, a lithium niobate piezoelectric chip (14) is provided in the center of the surface acoustic wave excitation platform (19), the two interdigital transducers (15) respectively excite two columns of surface acoustic waves, the two columns of surface acoustic waves propagate along the surface of the lithium niobate piezoelectric chip (14), and then form a surface acoustic wave pressure field (16) in the open space; the surface acoustic wave pressure field (16) drives the nanoparticles in the nanoparticle-photosensitive prepolymer mixed solution to gather at each acoustic radiation node to form a nanoparticle strip, and the nanoparticle strips at all acoustic radiation nodes form a nanoparticle strip array; Next, the interdigital transducer (15) is turned off; 6) Turning on the UV DLP projector (18) placed upside down above the printing liquid tank (20), the UV DLP projector (18) emits UV light downward, and the nanoparticle-photosensitive prepolymer mixed solution in the UV light irradiation area is cured and covers the nanoparticle strip array formed in step 5), forming a photocured layer having the thickness of the current printing layer, the photocured pattern, and the nanoparticle strip array, and then proceeding to step 8); 7) Turning on the UV DLP projector (18), the UV DLP projector (18) emits UV light downward, and the nanoparticle-photosensitive prepolymer mixed solution in the UV light irradiated area is solidified to form a photocured layer having the thickness of the current printing layer and the photocured pattern, and then proceeding to step 8); 8) Controlling the loading platform (17) to move downward, the moving distance being equal to the thickness of the next printing layer, and taking the next printing layer as the current printing layer; 9) Repeating steps 4) to 8) on the lower surface of the loading platform (17), sequentially forming light-cured layers corresponding to each printing layer from bottom to top until the printing is completed, thereby obtaining a printed component; 10) Post-processing the printed component to obtain a printed component.

8. The acoustic-assisted 3D printing method according to claim 7, wherein: In the process of printing the upper electrode layer (1) layer by layer using an acoustically assisted 3D printing device: in the step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 0.5-20 wt% of silver nanoparticles; in the step 2), the upper electrode layer (1) is divided into two printing layers, the two printing layers corresponding to the upper electrode layer film and the strip boss array, respectively, and the printing layer corresponding to the strip boss array is the first printing layer.

9. The acoustic-assisted 3D printing manufacturing method according to claim 7, characterized in that: In the process of printing the sensing layer (2) layer by layer using an acoustically assisted 3D printing device: in the step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5wt% barium titanate nanoparticles; in the step 2), the sensing layer (2) is divided into a plurality of printing layers, wherein each wide-range pressure sensing unit linear array / sensitive pressure sensing unit linear array is divided into two printing layers, and the two printing layers are distributed corresponding to the pre-printed layer (12) and the particle strip layer, and the pre-printed layer (12) is formed before the particle strip layer.

10. The acoustic-assisted 3D printing manufacturing method according to claim 7, characterized in that: In the process of printing the lower electrode layer (3) layer by layer using an acoustic-assisted 3D printing device: in the step 1), the nanoparticle-photosensitive prepolymer mixed solution is a photosensitive prepolymer containing 5wt% silver nanoparticles; the step 2) is specifically as follows: first, the lower electrode layer (3) is divided into two printing layers, the thickness of the first printing layer is the thickness of the lower electrode layer (3), and the thickness of the second printing layer is zero; then, the lower layer particle silver electrode array is split into two double-spacing distribution sub-patterns, and the particle strip spacing in the two double-spacing distribution sub-patterns is twice the particle strip spacing in the lower layer particle silver electrode array; finally, the horizontal projection pattern of the lower electrode film (11) is split into two strip array patterns, and the two strip array patterns correspond one-to-one to the two double-spacing distribution sub-patterns; the information of the two printing layers respectively includes the two double-spacing distribution sub-patterns and the corresponding strip array patterns.

Images