Piezoresistive sensor array and preparation method thereof
The piezoresistive sensor array with stretchable negative Poisson Island bridge structure was prepared through 3D printing technology, which solved the problem of easy damage to the sensor and strain signal interference in the tensile state, and achieved higher tensile performance and electrical signal stability.
Patent Information
- Application Number
- CN202510008120.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-03
- Publication Date
- 2025-06-20
AI Technical Summary
Existing tensile piezoresistive sensors are susceptible to irreversible damage in the tensile state, and the tensile strain signal interferes with the accuracy of the piezoresistive signal and affects the stability of the sensor.
A piezoresistive sensor array with tensile negative Poisson island bridge structure is prepared by using 3D printing technology. The hard island is combined with the soft bridge through structural design. The hard island is loaded with sensors, and the soft bridge bears tensile strain and improves the stability of the electrical signal.
It significantly improves the overall tensile performance and reliability of the sensor, reduces strain interference, and improves the electrical signal stability and mechanical response accuracy of the piezoresistive sensor array.
Smart Images
Figure CN120176914A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of flexible sensors, and particularly relates to a piezoresistive sensor array and a preparation method thereof. Background Art
[0002] Stretchable pressure sensors have broad application prospects and can be used to monitor physiological signals such as blood pressure, respiratory rate, and heart rate. Such sensors can also help track the performance and muscle activity of athletes, thereby optimizing training effects and preventing sports injuries. Especially in the field of bionic electronic skin, it enables robots to have the ability to sense pressure changes, thus enhancing their interaction with the environment. To enable robots to better adapt to complex environments and tasks, bionic skin needs to have sufficient flexibility and stretchability to conform to the shapes of various target objects and achieve accurate pressure measurement. However, in the stretched state, the sensitive layer of piezoresistive sensors is vulnerable to irreversible damage, and at the same time, the response of the sensor to tensile strain may also interfere with the accuracy of piezoresistive signals. Therefore, it is particularly important to develop a manufacturing method for pressure sensor arrays with excellent stretchability and reliability.
[0003] The production of stretchable piezoresistive sensors usually adopts two strategies: one is to design all components to be stretchable, and the other is to structure the substrate so that it concentrates strain at the interconnections, ensuring that the unit area is basically unaffected or bears the minimum strain. The first strategy allows for high integration, high density, excellent mechanical toughness, and flexibility. However, ensuring that each component of the device is stretchable is a challenge. Stretchable substrates including styrene-ethylene-butene-styrene (SEBS) and polydimethylsiloxane (PDMS) can withstand up to 100% stretching. However, it is a problem to enable other components such as electrodes and active layers to stretch synchronously with the substrate. Under a certain degree of tensile strain, piezoresistive sensors are prone to mechanical damage, and piezoresistive signals are easily interfered by strain signals during the stretching process, affecting the stability of the sensors.
[0004] The second "rigid island" method allows the integration of existing rigid electronic components without deformation. Specifically, the development of stretchable printed circuits has made it possible to integrate traditional electronic devices into stretchable configurations on rigid islands. A variety of methods have been used to fabricate soft / rigid islands, including molding, selective oxidation, connection domain methods, printing, and ultraviolet degradation techniques. Although these methods represent effective paths to achieve stretchable electronic devices, there are still many challenges to be solved. For example, complex processes and difficulties in achieving fine, high-resolution pattern drawing limit their practical applications. Summary of the Invention
[0005] The object of the present invention is to provide a piezoresistive sensor array with a 3D printable stretchable negative Poisson's island-bridge structure, aiming to enhance the stretchable piezoresistive sensor's resistance to tensile strain signal interference through a structured design of the piezoresistive sensor. The introduction of 3D printing technology enables the realization of fine-structured molding, combining rigid islands and soft bridges, with the rigid islands loading the sensors and the soft bridges bearing the tensile strain, further improving the electrical signal stability of the piezoresistive sensor array.
[0006] The present invention provides a preparation method for a piezoresistive sensor array, and the preparation method specifically includes the following steps: S1. Prepare photocurable 3D printing ink: By setting the addition ratio, isobornyl acrylate, benzyl acrylate, and photocurable resin are mixed, and then a photoinitiator is added. After mechanical stirring in a light-shielded environment, rigid substrate ink and soft substrate ink are obtained respectively. S2. Prepare MXene flakes: Hydrochloric acid solution and lithium fluoride powder are mixed and stirred to obtain a mixed solution. Aluminum titanium carbide powder is added to the mixed solution and stirred to obtain a suspension. The suspension is washed with deionized water until the pH of the supernatant is 6, and then the supernatant is collected, ultrasonically treated under an argon atmosphere, and centrifuged to obtain layered MXene flakes. S3. Prepare PU / MXene ink: Polyurethane is added to N,N-dimethylformamide, cooled after the first stirring treatment, and the MXene flakes prepared in step S2 are added. After the second stirring treatment, PU / MXene ink is obtained. S4. Photocure the soft substrate ink prepared in step S1 into a negative Poisson's island-bridge structure and a groove for placing the piezoresistive sensor, pour the rigid substrate ink prepared in step S1 into the groove, and obtain an interdigital electrode substrate after curing and forming. S5. Attach the interdigital electrode mask plate to the interdigital electrode substrate prepared in step S4, deposit a metal silver interdigital electrode by vacuum evaporation, and then remove the interdigital electrode mask plate. S6. Import the conical structure of the piezoresistive sensor array into the program of the photocuring printer, and obtain the conical structure of the piezoresistive sensor array after photocuring printing, washing, and drying with the soft substrate ink. S7. Spin-coat the PU / MXene ink prepared in step S3 on the conical structure prepared in step S6, soak it in water and then dry it, and buckle it on the metal silver interdigital electrode prepared in step S5 to finally obtain the piezoresistive sensor array.
[0007] Compared with the prior art, the present invention has the stretchable characteristics of the device, and the piezoresistive sensor has the stability against strain interference. By using the photocuring 3D printing technology, a substrate structure combining hardness and softness is prepared, enabling the piezoresistive sensor array to have intrinsic stretchability, which helps to adapt to complex deformation environments; by designing a negative Poisson's ratio island-bridge structure, the overall stretching performance of the device is significantly improved, ensuring its reliability under large strains; by combining the PU / MXene sensitive material and the optimized design of the microscopic conical structure of the sensing layer, the electrical signal sensitivity of the sensor under pressure loading is greatly improved, achieving a more accurate mechanical response; at the same time, the sensor array prepared by the 3D printing technology is more efficient than the traditional preparation method, with a simple process flow and easy to scale up production, having significant advantages.
[0008] In a possible implementation manner, in the step S1, the formulation of the hard substrate ink is as follows: isobornyl acrylate, benzyl acrylate, photocuring resin, and photoinitiator = 50:20:30:1, and the formulation of the soft substrate ink is as follows: isobornyl acrylate, benzyl acrylate, photocuring resin, and photoinitiator = 20:50:30:1.
[0009] Compared with the prior art, the higher proportion of isobornyl acrylate (50%) in the hard substrate ink of the present invention provides higher rigidity and hardness, which makes the hard substrate ink suitable for structural parts that require good mechanical stability; in addition, by adjusting the proportion of benzyl acrylate (50%), the negative Poisson's ratio characteristic of the material can be achieved, which means that when the material is stretched, it will expand in the vertical direction, and this characteristic is very useful for improving the energy absorption capacity and impact resistance; the higher content of benzyl acrylate endows the material with better flexibility and compliance, making it suitable for structures that require a certain degree of elasticity and adaptability, such as the "island-bridge" structure, which can better distribute stress when subjected to pressure or tension, reducing local stress concentration.
[0010] In a possible implementation manner, in the step S1, the parameters of mechanical stirring are as follows: the temperature is 15 - 25 °C, and the time is 8 - 10 h.
[0011] Compared with the prior art, the longer stirring time of the present invention can ensure that all components are fully mixed. Especially for additives such as photoinitiators, long-time stirring helps them to be evenly distributed in the resin matrix. At the same time, this temperature range will neither cause premature unnecessary chemical reactions (such as premature polymerization) of the material nor maintain sufficient fluidity for mixing.
[0012] In a possible implementation manner, in the step S1, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.
[0013] Compared with the prior art, the present invention uses the above materials as photoinitiators. TPO is an efficient photoinitiator, which is particularly good at absorbing ultraviolet light (UV) and rapidly decomposing to generate free radicals or cations after absorption, thereby initiating the polymerization reaction. TPO can almost immediately start initiating the polymerization reaction after contacting ultraviolet light, which not only speeds up the curing speed but also improves the production efficiency. The rapid curing reduces the risk of material property changes due to long-term exposure to air.
[0014] In a possible implementation manner, in the step S2, the mass ratio of lithium fluoride powder to aluminum titanium carbide powder is 1:1, and the concentration of the hydrochloric acid solution is 9 mol / L.
[0015] Compared with the prior art, the present invention uses a mass ratio of lithium fluoride to aluminum titanium carbide of 1:1. This ratio can ensure that there is enough LiF during the etching process to effectively neutralize by-products such as the generated AlF3, preventing it from redepositing between the MXene layers and thus hindering the further etching process. The high concentration of HCl can provide sufficient hydrogen ions (H + ), accelerating the dissolution of Group A elements (such as aluminum) between the aluminum titanium carbide layers and improving the etching efficiency. At the same time, the high-concentration acid solution also helps to maintain the pH value stability during the etching process, ensuring the continuous progress of the reaction.
[0016] In a possible implementation manner, in the step S2, the parameters of the stirring treatment are as follows: the temperature is 40 °C and the time is 24 h.
[0017] In a possible implementation manner, in the step S2, the time of the ultrasonic treatment is 1 h.
[0018] In a possible implementation manner, in the step S2, the parameters of the centrifugation treatment are as follows: the rotation speed is 3000 - 4000 rpm and the time is 5 min.
[0019] In a possible implementation manner, in the step S3, the mass ratio of polyurethane to MXene is 1:1, the concentration of polyurethane in N,N-dimethylformamide is 0.2 - 0.5 g / ml, the temperature of the first stirring treatment is 65 - 80 °C, and the time is 0.5 - 2 h; In a possible implementation manner, the time of the second stirring treatment is 0.5 - 2 h and the temperature is 15 - 25 °C.
[0020] In a possible implementation manner, in the step S4 and the step S6, the parameters of the photocuring printing are the same, and the parameters are as follows: the layer height is set to 0.05 mm, the curing time of the first layer is 1.7 s, and the curing time of other printing layers is 1.2 s.
[0021] Compared with the prior art, the present invention adopts the above parameters. The layer height of 0.05 mm ensures a very high printing resolution and can achieve a structure with rich details, which is crucial for manufacturing grooves, interdigital electrode substrates, and conical structures in a tiny and complex piezoresistive sensor array. A longer curing time for the first layer can ensure a strong bond between the first layer and the printing platform, preventing warping or detachment. For the other layers except the first layer, a shorter curing time is adopted, which significantly improves the printing speed on the premise of ensuring the curing effect.
[0022] In a possible implementation manner, the interdigital electrode substrate also undergoes ultrasonic cleaning treatment, and the parameters of the ultrasonic cleaning treatment are as follows: the cleaning liquid is 95% anhydrous ethanol, the cleaning frequency is 20 - 80 kHz, the number of cleaning times is 3 times, and the ultrasonic cleaning time for each time is 10 min.
[0023] In a possible implementation manner, in the step S7, the parameters of spin coating are as follows: the volume of the spin-coated PU / MXene ink is 0.5 - 1 mL for each sensor, the spin coating speed is 6000 - 9000 rad / min, and the spin coating time is 60 - 120 s.
[0024] The second object of the present invention is to provide a piezoresistive sensor array, which includes a plurality of negative Poisson island bridges connected end to end in a circular shape, and the circular cavity of each negative Poisson island bridge is divided into a plurality of first installation areas. A second installation area is formed between the outer walls of two adjacent negative Poisson island bridges. A piezoresistive sensor unit is arranged in each of the first installation areas and the second installation areas, and the outer wall of each piezoresistive sensor unit is fixedly connected to the negative Poisson island bridge.
[0025] In a possible implementation manner, the piezoresistive sensor unit includes a soft substrate, a groove for placing a piezoresistive sensor is arranged in the soft substrate, an interdigital electrode substrate is further arranged between the piezoresistive sensor and the soft substrate, the piezoresistive sensor includes a plurality of conical structures and metal silver interdigital electrodes, and a PU / MXene ink layer is spin-coated on each conical structure, and the PU / MXene ink layer is electrically connected to the metal silver interdigital electrode. Description of the Drawings
[0026] Figure 1 It is a schematic diagram of the model structure of the 3D printed stretchable piezoresistive sensor array with a negative Poisson structure of the present invention; Figure 2 It is a SEM image of spin-coating the PU / MXene sensitive material on the sensor conical structure substrate; Figure 3 It is a schematic diagram of a buckle structure for improving the stability of the sensor; Figure 4It is a graph of the response time and recovery time of a piezoresistive sensor; Figure 5 It is the electrical signal stability test of a piezoresistive sensor, comparing the electrical signal responses in the unstretched state and at 135% strain. Specific embodiments
[0027] To make the above objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.
[0028] It should be noted that the endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.
[0029] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or facilitating citation. Such definitions herein should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise specified, the use of commercially available kits, reagents, and instruments is carried out according to the protocols and parameters given by the manufacturers.
[0030] The technical effects of the present invention will be described below in conjunction with specific embodiments.
[0031] As Figure 1 shown, the piezoresistive sensor array of the present invention includes multiple negative Poisson island bridges connected end to end in a circular arrangement, and the circular cavity of each negative Poisson island bridge is divided into multiple first installation areas. A second installation area is formed between the outer walls of adjacent negative Poisson island bridges. A piezoresistive sensor unit is provided in each first installation area and the second installation area, and the outer wall of each piezoresistive sensor unit is fixedly connected to the negative Poisson island bridge; wherein, the piezoresistive sensor unit includes a soft substrate, a groove for placing a piezoresistive sensor is provided in the soft substrate, and an interdigital electrode substrate is further provided between the piezoresistive sensor and the soft substrate. The piezoresistive sensor includes multiple conical structures and metal silver interdigital electrodes, and a PU / MXene ink layer is spin-coated on each conical structure, and the PU / MXene ink layer is electrically connected to the metal silver interdigital electrodes.
[0032] In a preferred embodiment, as Figure 3 shown, the connection method of the metal silver interdigital electrode and the piezoresistive sensor array structure coated with spin-coated PU / MXene ink is to align and fasten the snap structures preset on the metal silver interdigital electrode and the piezoresistive sensor.
[0033] Example 1 This example provides a piezoresistive sensor array with a 3D-printed stretchable negative Poisson structure, which is prepared by the following method: S1: Preparation of photocurable 3D printing ink: Mix IBOA, BA, AUD, and TPO in a ratio of IBOA:BA:AUD:TPO = 20:50:30:1, and mechanically stir for 8 h in a light-shielded environment at 25 °C to obtain soft-IBA ink for photocuring the printed sensor array; adjust the material ratio to IBOA:BA:AUD:TPO = 50:20:30:1, and mechanically stir under the same conditions to obtain stiff-IBA ink for photocuring the printed sensor array; S2: Preparation of MXene flakes: Mix 9 mol / L, 40 mL of HCl solution with 2.0 g of LiF powder and stir for 30 min. Then add 2.0 g of Ti3AlC2 powder to the mixed solution and stir at 40 °C for 24 h. Wash the obtained suspension with deionized water until the pH of the supernatant is 6. Ultrasonically treat the collected supernatant in an Ar atmosphere for 1 h and centrifuge at 3000 rpm for 5 min to obtain layered MXene flakes, which are freeze-dried for later use; S3: Preparation of PU / MXene ink: Add 1.5 g of PU to 6 mL of DMF, stir thoroughly at 65 °C, and add 1.2 g of MXene flakes prepared in step S2 after cooling. Stir for 1 h to obtain PU / MXene ink; S4: Preparation of the stretchable negative Poisson island-bridge structure: Photocure the soft-IBA ink prepared in step S1 into a negative Poisson island-bridge structure. Among them, the island structure is only formed but left empty inside. Then pour the stiff-IBA ink into the island and cure it to form an interdigital electrode substrate. After the sample is formed, ultrasonically clean it in a beaker filled with ethanol, then dry it in a vacuum drying oven. Next, use a laser cutter to cut a PET board to obtain an interdigital electrode mask template, stick it on the prepared interdigital electrode substrate, and deposit a 200-nm-thick metal silver interdigital electrode by vacuum evaporation; S5: Preparation of the cone structure of the piezoresistive sensor: Use the soft-IBA ink prepared in step S1 to perform photocuring printing on the piezoresistive sensor structure, introduce the cone structure of the piezoresistive sensor into the photocuring printer, and after the machine automatically prints, immerse the sample in a beaker containing ethanol for ultrasonic cleaning, and then put it in a vacuum drying oven for drying to obtain the structure of the piezoresistive sensor array; S6: Coating and assembly of sensitive layer of stretchable piezoresistive sensor array: Spin-coat the PU / MXene ink obtained in step S3 at a rate of 7000 rad / min for 60 s on the conical structure of the piezoresistive sensor prepared in step S5, wherein the volume of PU / MXene dripped on each sensor is 0.5 mL. Then, soak the sample in water and place it in a vacuum drying oven for drying, and then buckle it on the interdigitated electrode array structure obtained in step S4 to obtain a piezoresistive sensor array with a stretchable negative Poisson structure.
[0034] Example 2 This embodiment provides a 3D printed stretchable negative Poisson structure piezoresistive sensor array, which is prepared by the following preparation method: S1: Preparation of photocurable 3D printing ink: IBOA, BA, AUD, and TPO were mixed at a ratio of IBOA:BA:AUD:TPO=20:50:30:1, respectively, and mechanically stirred for 9 h in a light-shielded environment at 20 °C to obtain soft-IBA ink for photocurable printing of sensor arrays; the material ratio of IBOA:BA:AUD:TPO was adjusted to 50:20:30:1, and mechanically stirred under the same conditions to obtain stiff-IBA ink for photocurable printing of sensor arrays; S2: Preparation of MXene flakes: After 9 mol / L, 40 mL of HCl solution and 2.0 g of LiF powder were mixed and stirred for 30 min, 2.0 g of Ti3AlC2 powder was added to the mixed solution and stirred at 40 °C for 24 h. The obtained suspension was washed with deionized water until the pH of the supernatant was 6. The collected supernatant was ultrasonically treated for 1 h under Ar atmosphere and centrifuged at 3500 rpm for 5 min to obtain layered MXene flakes, which were freeze-dried for later use. S3: Preparation of PU / MXene ink: 1.2 g PU was added to 4 mL DMF, and stirred at 70 °C. After cooling, 1.0 g MXene flakes prepared in step S2 were added, and the PU / MXene ink was obtained after stirring for 1.5 h. S4: Preparation of the stretchable negative Poisson island-bridge structure: The soft-IBA ink prepared in step S1 is used for photocuring printing to form a negative Poisson island-bridge structure. Among them, the island structure is only formed but left empty inside. Then, the stiff-IBA ink is poured into the island and cured to form an interdigital electrode substrate. After the sample is formed, it is ultrasonically cleaned in a beaker filled with ethanol, and then dried in a vacuum drying oven. Next, a PET board is cut by laser to obtain an interdigital electrode mask template, which is pasted on the obtained interdigital electrode substrate. By using the vacuum evaporation method, a metal silver interdigital electrode with a thickness of 200 nm is deposited; S5: Preparation of the piezoresistive sensor conical structure: The soft-IBA ink prepared in step S1 is used for photocuring printing of the piezoresistive sensor structure. The piezoresistive sensor conical structure is introduced into the photocuring printer. After the machine automatically finishes printing, the sample is ultrasonically cleaned in a beaker filled with ethanol, and then dried in a vacuum drying oven to obtain the structure of the piezoresistive sensor array; S6: Coating and assembly of the sensitive layer of the stretchable piezoresistive sensor array: As Figure 2 shown, the PU / MXene ink obtained in step S3 is spin-coated on the piezoresistive sensor conical structure prepared in step S5 at a rate of 6000 rad / min for 90 s. Among them, the volume of PU / MXene dropped on each sensor is 0.8 mL. Then, the sample is soaked in water and then placed in a vacuum drying oven to dry. It is buckled on the interdigital electrode array structure obtained in step S4 to obtain a stretchable piezoresistive sensor array with a negative Poisson structure.
[0035] Example 3 This example provides a 3D printed stretchable piezoresistive sensor array with a negative Poisson structure, which is obtained by the following preparation method: S1: Preparation of the photocuring 3D printing ink: IBOA, BA, AUD, and TPO are mixed in a ratio of IBOA:BA:AUD:TPO = 20:50:30:1. After mechanical stirring for 10 h in a light-shielded environment at 15 °C, the soft-IBA ink for photocuring printing the sensor array is obtained; the material ratio is adjusted to IBOA:BA:AUD:TPO = 50:20:30:1, and mechanical stirring is carried out under the same conditions to obtain the stiff-IBA ink for photocuring printing the sensor array; S2: Preparation of MXene flakes: After mixing 40 mL of 9 mol / L HCl solution with 2.0 g of LiF powder and stirring for 30 min, 2.0 g of Ti3AlC2 powder was added to the mixed solution and stirred at 40 °C for 24 h. Then, the obtained suspension was washed with deionized water until the pH of the supernatant was 6. The collected supernatant was ultrasonically treated for 1 h under an Ar atmosphere and centrifuged at 3000 - 4000 rpm for 5 min to obtain layered MXene flakes, which were freeze-dried for later use; S3: Preparation of PU / MXene ink: 2.0 g of PU was added to 8 mL of DMF and stirred thoroughly at 80 °C. After cooling, 1.8 g of the MXene flakes prepared in step S2 was added and stirred for 2 h to obtain PU / MXene ink; S4: Preparation of stretchable negative Poisson's island bridge structure: The soft-IBA ink prepared in step S1 was used for photocuring printing to form a negative Poisson's island bridge structure. Among them, the island structure was only formed but left empty inside. Then, the stiff-IBA ink was poured into the island and cured to form an interdigital electrode substrate. After the sample was formed, it was ultrasonically cleaned in a beaker filled with ethanol and then dried in a vacuum drying oven. Next, a PET plate was cut using a laser cutter to obtain an interdigital electrode mask template, which was pasted on the prepared interdigital electrode substrate. Using the vacuum evaporation method, a 200 nm thick metal silver interdigital electrode was deposited; S5: Preparation of piezoresistive sensor conical structure: The soft-IBA ink prepared in step S1 was used for photocuring printing of the piezoresistive sensor structure. The piezoresistive sensor conical structure was introduced into the photocuring printer. After the machine automatically completed printing, the sample was ultrasonically cleaned in a beaker filled with ethanol and then dried in a vacuum drying oven to obtain the structure of the piezoresistive sensor array; S6: Coating and assembly of the sensitive layer of the stretchable piezoresistive sensor array: The PU / MXene ink obtained in step S3 was spin-coated on the piezoresistive sensor conical structure prepared in step S5 at a rate of 8000 rad / min for 120 s. Among them, the volume of PU / MXene dropped on each sensor was 1.0 mL. Then, the sample was soaked in water and placed in a vacuum drying oven for drying, and buckled on the interdigital electrode array structure obtained in step S4 to obtain a stretchable negative Poisson's structure piezoresistive sensor array.
[0036] The inventor conducted performance testing on the 3D printed stretchable negative Poisson's structure piezoresistive sensor array prepared in Example 3. Figure 4 It is the response time and recovery time graph of the piezoresistive sensor; Figure 5 It is the electrical signal stability test of the piezoresistive sensor, comparing the electrical signal corresponding situations in the unstretched state and at 135% strain. From Figure 4It can be seen that the sample has a good piezoresistive-electrical signal response rate: the response time is about 0.8 - 1.2 s. In addition, the sample has good stretchability and stable sensing performance under strain. From Figure 5 It can be seen that the sample can still maintain the electrical signal stability under a strain of 135%, and has the same current change rate (ΔI / I0) as the original state.
[0037] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.
Claims
1. A method for preparing a piezoresistive sensor array, characterized in that: The preparation method specifically comprises the following steps: S1. Preparing photocurable 3D printing ink: mixing isobornyl acrylate, benzyl acrylate and photocurable resin by setting the adding ratio, adding a photoinitiator, and mechanically stirring under a light-shielding environment to obtain a hard substrate ink and a soft substrate ink respectively; S2. Preparation of MXene flakes: mixing hydrogen chloride solution and lithium fluoride powder to obtain a mixed solution, adding titanium aluminum carbide powder to the mixed solution and stirring to obtain a suspension, washing the suspension with deionized water until the pH of the supernatant is 6, and then collecting the supernatant and placing it in an argon atmosphere for ultrasonic treatment and then centrifugation to obtain layered MXene flakes; S3, preparing PU / MXene ink: adding polyurethane to N,N-dimethylformamide, stirring once and cooling, adding the MXene flakes obtained in step S2, stirring twice and obtaining PU / MXene ink; S4, using the soft substrate ink prepared in step S1 to perform photocuring printing to form a negative Poisson's island bridge structure and a groove for placing a piezoresistive sensor, pouring the hard substrate ink prepared in step S1 into the groove, and performing curing and molding to obtain an interdigital electrode substrate; S5, attaching an interdigital electrode mask plate to the interdigital electrode substrate obtained in step S4, using a vacuum evaporation method to deposit metal silver interdigital electrodes, and then taking out the interdigital electrode mask plate; S6, importing the cone structure of the piezoresistive sensor array into a program of a photocuring printer, using soft substrate ink for photocuring printing, and then cleaning and drying to obtain the cone structure of the piezoresistive sensor array; S7. Spin-coat the PU / MXene ink prepared in step S3 on the cone structure prepared in step S6, soak it in water and then dry it, and then buckle it on the metal silver interdigital electrode prepared in step S5 to finally obtain a piezoresistive sensor array.
2. The preparation method according to claim 1, characterized in that In the step S1, the ratio of the hard substrate ink is as follows: isobornyl acrylate, benzyl acrylate, photocurable resin and photoinitiator = 50:20:30:1, and the ratio of the soft substrate ink is as follows: isobornyl acrylate, benzyl acrylate, photocurable resin and photoinitiator = 20:50:30:
1.
3. The preparation method according to claim 1, characterized in that: In step S1, the parameters of mechanical stirring are as follows: temperature is 15-25°C, time is 8-10h; And / or, the photoinitiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide.
4. The preparation method according to claim 1, characterized in that: In the step S2, the mass ratio of lithium fluoride powder to titanium aluminum carbide powder is 1:1, and the concentration of hydrogen chloride solution is 9 mol / L; And / or, the parameters of the stirring treatment are as follows: temperature is 40° C., and time is 24 h.
5. The preparation method according to claim 1, characterized in that: In step S2, the ultrasonic treatment time is 1 hour; And / or, the parameters of the centrifugal treatment are as follows: the rotation speed is 3000-4000 rpm, and the time is 5 min.
6. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of polyurethane to MXene is 1:1, the concentration of polyurethane in N,N-dimethylformamide is 0.2-0.5 g / ml, the temperature of the stirring treatment is 65-80° C., and the time is 0.5-2 h; And / or, the secondary stirring treatment time is 0.5-2h and the temperature is 15-25°C.
7. The preparation method according to claim 1, characterized in that: In step S4 and step S6, the parameters of the photocuring printing are the same, and the parameters are as follows: the layer height is set to 0.05 mm, the curing time of the first layer is 1.7 s, and the curing time of other printed layers is 1.2 s; And / or, the interdigital electrode substrate is further subjected to ultrasonic cleaning treatment, and the parameters of the ultrasonic cleaning treatment are as follows: the cleaning liquid is 95% anhydrous ethanol, the cleaning frequency is 20-80kHz, the cleaning times is 3 times, and each ultrasonic cleaning time is 10 minutes.
8. The preparation method according to claim 1, characterized in that: In step S7, the spin coating parameters are as follows: the volume of the spin-coated PU / MXene ink is 0.5-1 mL per sensor, the spin coating speed is 6000-9000 rad / min, and the spin coating time is 60-120 s.
9. A piezoresistive sensor array, characterized in that: The piezoresistive sensor array is manufactured by the preparation method as described in any one of claims 1 to 8, comprising a plurality of negative Poisson island bridges connected end to end in a ring-shaped arrangement, and the annular cavity of each of the negative Poisson island bridges is divided into a plurality of first installation areas, and a second installation area is formed between the outer walls of two adjacent negative Poisson island bridges, a piezoresistive sensor unit is arranged in each of the first installation area and the second installation area, and the outer wall of each of the piezoresistive sensor units is fixedly connected to the negative Poisson island bridge.
10. The piezoresistive sensor array according to claim 9, characterized in that: The piezoresistive sensor unit includes a soft substrate, a groove for placing the piezoresistive sensor is arranged in the soft substrate, and an interdigitated electrode substrate is also arranged between the piezoresistive sensor and the soft substrate. The piezoresistive sensor includes a plurality of conical structures and metal silver interdigitated electrodes, and a PU / MXene ink layer is spin-coated on each of the conical structures, and the PU / MXene ink layer is electrically connected to the metal silver interdigitated electrodes.