Method for synergistically enhancing sensing performance of sensor by using microstructure design and material regulation and control as well as product and application thereof

Abstract

The invention provides a method for synergistically enhancing the sensing performance of a sensor by using microstructure design and material regulation and control as well as a product and application thereof. The method specifically comprises the following steps: S1, fitting a stress-strain curve of ionic gel by using an Ogden model, and performing design simulation of a microstructure by using a quasi-columnar microstructure as a seed model for parameter adjustment to obtain a linear microstructure array model; s2, the microstructure model is exported, a resin mold is obtained through 3D printing, an ionic liquid precursor is poured into the mold, demolding is conducted after curing, and the sensing material with the linear microstructures orderly distributed on the surface is obtained; and S3, taking the sensing material as an intermediate ion functional layer, and assembling into the ionizing flexible pressure sensor. According to the invention, the functional material with a complex structure is integrally prepared by designing a linear microstructure and regulating and controlling the proportion of the ionic gel functional material and combining a 3D printing technology and an ionic liquid reverse molding technology, and the prepared sensor can realize ultra-sensitivity, high linearity and wide measuring range of which the linearity degree is higher than 0.997 within 0-2MPa.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensor preparation methods, and specifically relates to a method for realizing synergistic enhancement of sensor sensing performance by utilizing microstructure design and material regulation, as well as a product and application thereof. Background Art

[0002] Flexible pressure sensors are soft, light, bendable, and stretchable. They can fit irregular surfaces and achieve high-precision pressure sensing and real-time monitoring. They have shown great potential and wide application value in many cutting-edge fields, which also marks the progress of sensing technology towards intelligence and multifunctionality. It not only provides more convenient and intelligent solutions for modern society, but also opens up new directions and possibilities for the development of future science and technology.

[0003] Flexible pressure sensors are usually made of a middle sensing functional layer and two layers of flexible electrodes. According to the different principles of sensor signal conversion, flexible pressure sensors are mainly divided into four categories: capacitive, resistive, piezoelectric and triboelectric pressure sensors. Compared with resistive sensors, capacitive sensors have a wider pressure test range and higher stability; and compared with pressure and triboelectric sensors, they are not restricted by signal dynamics and statics. Not only that, capacitive pressure sensors also have the characteristics of high drift stability, high sensitivity, low power consumption, and simple structure. They are considered to be the most promising choice for high-performance sensing and have been widely studied. Capacitive pressure sensors are mainly divided into two categories: traditional parallel plate capacitors based on the principle of parallel plate capacitance and ion-type flexible pressure sensors based on the principle of double electric layer.

[0004] A parallel plate capacitor consists of two parallel metal plates and a dielectric layer in between, where the dielectric layer is usually air or a dielectric layer with a high dielectric constant. The capacitance value formed will change with the distance between the two plates, thereby achieving a corresponding mapping for different pressures. Since the relative area and distance changes of parallel plate capacitors are relatively limited, researchers usually adjust the relative dielectric constant of the dielectric to prepare capacitors with the best performance.

[0005] Another type of capacitive pressure sensor is an ion-type pressure sensor based on the double-layer principle. Due to its extremely high sensitivity, it is considered to be the core way to develop highly sensitive pressure sensors. Figure 1 As shown in the figure, it is composed of two layers of flexible electrodes and an intermediate ion functional material layer. Due to the attraction between charges, a double electric layer is formed at the interface between ions and electrons, resulting in a larger unit area capacitance. When pressure is applied, the ion functional material layer is compressed, forming more and more capacitors in parallel at the interface, greatly increasing the capacitance value.

[0006] In order to accurately collect signals in different application scenarios, researchers often need to select appropriate designs and materials, find the best balance, and customize the sensor to meet the requirements of specific applications. The key technical difficulty is that when optimizing a certain performance indicator, other indicators are often adversely affected, which is manifested in the contradiction between the sensitivity, linearity and range of the sensor. High sensitivity is very important for flexible pressure sensors because it can detect extremely small pressure changes and ensure that the sensor can still provide accurate and reliable measurements in complex and changing environments. Linear response is also important for flexible pressure sensors because it ensures that the relationship between pressure and sensor output signal remains consistent and predictable, thereby simplifying data processing and calibration processes and improving measurement accuracy and reliability. In addition, the wide working range allows the sensor to provide stable and accurate measurements in various pressure environments, and can effectively respond from slight contact to greater pressure, which provides a certain degree of reliability for monitoring different levels of pressure in a wide range of application scenarios.

[0007] Generally, increasing the sensitivity will cause the sensor's range to become narrower. This is because high-sensitivity designs are usually optimized for small changes. When the input signal exceeds a certain range, the mismatch between the pressure increment generated by the sensor and the electrical signal leads to signal saturation under high pressure, making it difficult to ensure accurate measurement over a wide range, which in turn hinders the sensor's ability to achieve linear response over the full range.

[0008] It can be seen that how to solve the technical problem that traditional sensors cannot achieve both high sensitivity, high linearity and wide range sensing performance is of great significance to technical personnel in this field. Summary of the invention

[0009] In view of the technical problem that conventional sensors in the prior art cannot achieve high sensitivity, high linearity, and wide range, the present invention provides a method for realizing synergistic enhancement of sensor performance by using microstructure design and material regulation. The synergistic growth of various sensor performances is comprehensively realized by coordinating the design of the sensor material layer microstructure and the regulation of the amount of functional materials.

[0010] To achieve the above object, the present invention provides a method for synergistically enhancing the sensing performance of a sensor by utilizing microstructure design and material regulation, comprising the following steps:

[0011] S1 fits the stress-strain curve of the ion gel with the Ogden model, takes the columnar microstructure as the seed model for parameter adjustment, performs microstructure design simulation, and obtains a linear microstructure array model;

[0012] S2 exports the obtained microstructure model, automatically prints a resin mold through a 3D printer, pours the ionic liquid precursor into the obtained mold, and demolds it after curing to obtain a sensing material with an orderly distributed linear microstructure on the surface;

[0013] S3 uses the obtained sensing material as an intermediate ion functional layer to assemble an ion-type flexible pressure sensor.

[0014] In a preferred embodiment, in step S2, the preparation method of the ionic liquid precursor comprises the following steps: uniformly mixing a polymer monomer, an ionic liquid, a cross-linking agent and an initiator to obtain; wherein the mass ratio of the cross-linking agent to the polymer monomer is (0.05-0.3):1; preferably, the mass ratio of the cross-linking agent to the polymer monomer is 0.05:1, 0.1:1, 0.2:1, 0.3:1.

[0015] More preferably, the polymer monomers are composed of acrylonitrile monomers and ethyl acrylate monomers; the ionic liquid includes 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt; the crosslinking agent includes trimethylolpropane trimethacrylate; the initiator includes (2,4,6-trimethylbenzoyl) diphenylphosphine oxide;

[0016] Most preferably, in the polymer monomer, the mass ratio of ethyl acrylate monomer to acrylonitrile monomer is 5:5-2:8; the mass ratio of the ionic liquid to the polymer monomer is (0.5-1.5):1; the mass ratio of the cross-linking agent to the polymer monomer is (0.05-0.3):1; the mass ratio of the initiator to the polymer monomer is (0.003-0.007):1.

[0017] In a preferred embodiment, in step S2, the surface microstructure of the prepared sensing material is specifically composed of a plurality of special-shaped units arranged in rows staggered head to tail, each of which has a head with a semicircular cross-section and a tail that is flattened and extends backward along the head.

[0018] In a preferred embodiment, in step S3, the prepared ionization type flexible pressure sensor can achieve a linearity higher than 0.997 within 0-2 MPa.

[0019] In the present invention, the problem of low sensitivity is solved by selecting an ion-type pressure sensor; a linear microstructure template with ultra-high linear response is designed through simulation; complex structures and functional materials are integrated through 3D printing technology and ionic liquid molding technology; and the sensing function and mechanical properties of the sensing material are coordinated by adjusting the ionic liquid ratio, thereby achieving high linearity and wide range at the same time, thereby solving the common contradiction between high sensitivity, high linearity and wide range.

[0020] In a preferred embodiment, in step S1, the ion gel is obtained by polymerization of the ionic liquid precursor in step S2; preferably, the polymerization reaction conditions are: light source power 6-10w, wavelength 365nm, light polymerization time 40min-2h.

[0021] In a preferred embodiment, in step S1, the columnar microstructure includes a columnar height (h), horizontal radii of the head and tail sides (x1, x2), and vertical radii of the head and tail sides (y1, y2).

[0022] In a preferred embodiment, in step S1, the constraint conditions of the columnar microstructure include: the lower limit of each size is not less than 10 μm, the upper limit is not more than 100 μm, x2>x1, y2 <y1。

[0023] In a preferred embodiment, in step S1, simulation results show that when the ratio of the vertical radius to the horizontal radius of the microstructure head is less than 4 (satisfying 4x1≥y1), collapse of the structure during compression can be avoided.

[0024] In a preferred embodiment, in step S1, the design simulation result of the microstructure is: x1=25 μm, y1=100 μm, x2=65 μm, y1=10.2 μm.

[0025] In a preferred embodiment, step S2 specifically includes:

[0026] S21 uses software to check, repair and slice the calculated linear microstructure array model;

[0027] S22 imports the sliced ​​model into a 3D printer for automatic printing to obtain a resin mold;

[0028] S23 takes out the resin mold and cleans it;

[0029] S24: pouring the ionic liquid precursor into the cleaned mold, and removing the mold after curing.

[0030] Preferably, in step S21, the calculated linear microstructure array model is imported into Materialise Magics software for model defect inspection and repair to reduce the memory size of the model, and an STL format model suitable for slicing is obtained; the sliced ​​model is imported into a printing slicing tool (BMF-3Dslicer) for slicing; more preferably, the platform accuracy is 2 μm, the layer thickness is 5 μm, and the total area of ​​3D printing is controlled within 38.4 mm·21.6 mm.

[0031] Preferably, in step S22, the model of the 3D printer is BMF S130 (digital light processing type), and more preferably, the 3D printer and the fixing device are leveled so that the horizontal deviation around them does not exceed 5 μm.

[0032] Preferably, in step S23, the purpose of the cleaning is to remove the resin precursor remaining in the cured template. Therefore, conventional methods known to those skilled in the art can be adopted to achieve the aforementioned purpose; for example, the printed material is taken out and placed in ethanol and deionized water respectively for ultrasonication for 30 minutes, and the ultrasonicated material is placed in an oven at 50°C for 2 hours.

[0033] Preferably, in step S24, the curing method can adopt a conventional method known to those skilled in the art, such as light curing; more preferably, the curing conditions are: light source power 6-10w, wavelength 365nm, light polymerization time 40min-2h.

[0034] Another object of the present invention is to provide a flexible pressure sensor prepared by any of the above methods, which has high sensitivity, high linearity and wide range.

[0035] In the present invention, a linear microstructure is prepared on one side of the sensing material layer (ion gel) by combining 3D printing technology with ionic liquid molding technology. It should be noted that the present invention can also combine two 3D printing molds to prepare a linear microstructure on both sides of the sensing material layer (ion gel), which is also within the protection scope of the present invention.

[0036] Another object of the present invention is to provide a flexible pressure sensor prepared by any of the above methods with high sensitivity, high linearity and wide range for application in health monitoring, wearable devices, robot touch and virtual reality.

[0037] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0038] The present invention provides a general method for realizing the synergistic enhancement of the sensing performance of the sensor by utilizing microstructure design and material regulation. First, a linear microstructure model is obtained by computer simulation calculation, and then the linear range of the sensor is broadened by regulating the proportion of the crosslinking agent in the gel material, so that the linear acquisition of the gel material in the high-pressure scenario is possible. In terms of the specific method for preparing the sensing material, the present invention integrates the complex structure and functional materials through 3D printing technology combined with ionic liquid reverse molding technology, and can quickly obtain a linear microstructure sensing material with a specific function. Then, it is assembled into an ion-type flexible pressure sensor, which can solve the problem that the sensor in the prior art cannot simultaneously take into account high sensitivity, high linearity and wide range. The sensor prepared by the present invention can achieve ultra-sensitivity, high linearity and wide range with a linearity higher than 0.997 within 0-2MPa, which is much higher than all sensors currently on the market, and has the world's leading sensing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] These and / or other aspects and advantages of the present invention will become more clear and easier to understand from the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0040] Figure 1 The working principle of the ionization type flexible pressure sensor;

[0041] Figure 2 This is a schematic diagram of the ultra-high linear response of an ionization-type flexible pressure sensor in an embodiment of the present invention;

[0042] Figure 3 The measured stress-strain curve of the P(EA-co-AN) material in the embodiment of the present invention and the Ogden model fitting curve;

[0043] Figure 4 A schematic diagram of the morphology of a columnar microstructure and five geometric parameters used in an embodiment of the present invention;

[0044] Figure 5 The deformation effect of different aspect ratios on the structure in the embodiment of the present invention, wherein (a) the simulation curve of contact area with pressure under different aspect ratios and (b) the structural simulation diagram of buckling deformation;

[0045] Figure 6 The simulated response curve between the microstructure morphology and the pressure-contact area is finally determined for the embodiment of the present invention, wherein: (a) the morphology of the microstructure: the upper figure is a top view and the lower figure is a side view; (b) the simulated pressure and contact area output curve of the microstructure;

[0046] Figure 7 This is a surface scanning electron microscope image of a sensing material layer having a linear microstructure prepared in an embodiment of the present invention;

[0047] Figure 8 A comparison chart of the strength and modulus of the ion gel functional material at different cross-linking ratios in the embodiment of the present invention;

[0048] Fig. 9 This is a comparison chart of the effects of different modulus gel materials on the linear range of the sensor in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but it should be understood that the protection scope of the present invention is not limited to the specific implementation methods.

[0050] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art, and the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The reagents used in the present invention are analytically pure unless otherwise specified.

[0051] The embodiments of the present invention provide a method for synergistically enhancing the sensing performance of a sensor by utilizing microstructure design and material regulation, as well as a product and application thereof, thereby solving the common problem in the prior art that current sensors cannot simultaneously take into account high sensitivity, high linearity and wide range, resulting in poor sensing performance.

[0052] The technical solution in the present invention is to solve the above problems, and the overall idea is as follows:

[0053] Example

[0054] A method for synergistically enhancing the sensing performance of a sensor by utilizing microstructure design and material regulation:

[0055] (I) Select sensor type:

[0056] In order to solve the problem of low sensitivity, the sensor of the present invention adopts an ion-type flexible pressure sensor. Compared with the traditional parallel plate capacitor, the distance between the electrode plate and the microstructure surface of the capacitor formed by the ion-type pressure sensor is extremely small, and the charge separation distance of the double-layer capacitor is only 5-10 angstroms. According to the calculation formula of the parallel plate capacitor, the capacitance value is inversely proportional to the distance between the two electrodes. Therefore, under the condition of the same facing area, the double-layer capacitance value formed at the interface is much larger than the capacitance value of the traditional parallel plate capacitor. Such a large unit area capacitance also increases the capacitance signal size of the ion-type pressure sensor by 5 orders of magnitude on the original basis, greatly improving the sensitivity and signal-to-noise ratio of the sensor. In this embodiment, the electrode layer of the sensor used includes a PI / Cu composite film; the encapsulation layer includes a PDMS film; the specific preparation method includes: aligning and encapsulating the upper encapsulation layer, the upper electrode layer, the sensing material layer, the lower electrode layer and the lower encapsulation layer from top to bottom.

[0057] (II) Factors affecting the linear response of the sensor:

[0058] The mechanism of why traditional resistance pressure sensors and parallel plate capacitance sensors are difficult to achieve linear response is analyzed: Compared with traditional resistance principle sensors, the sensitive elements of resistance sensors are usually made of semiconductor materials or metals, and the relationship between the resistance of these materials and stress or strain is often not linear; and the contact resistance between the electrodes and the sensitive elements of the resistance sensor may change with pressure or strain, and this change is usually not linear, thus affecting the overall linearity of the sensor. This is determined by the intrinsic characteristics of the material, and it is difficult to achieve a linear response under a wide range. For parallel plate capacitance sensors, when the distance d between the electrodes changes, the change in capacitance C is inversely proportional to it, that is, the capacitance changes nonlinearly with distance. Similarly, the dielectric material in the sensor is also susceptible to changes in external factors such as temperature, humidity, etc., which will also cause the capacitance response to be nonlinear.

[0059] However, for ion-type pressure sensors, the capacitance of the double layer is only related to the contact area of ​​the ion-electron interface, and has nothing to do with the spacing and facing area between the two flexible electrodes. Specifically, for ion-type pressure sensors, charge separation is completely determined by material properties such as the type and density of the ion gel material, which means that the capacitance per unit area is constant. Therefore, the capacitance value (C) of the ion-type interface is determined by the contact area (A) of the ions and electrons, as shown in Formula 1-1 and Figure 2 As shown:

[0060] C=UAC·A (1-1)

[0061] The total capacitance (C) of the ionization type pressure sensor is composed of a microstructured ionization interface capacitor and a flat ionization interface capacitor in series.

[0062] The specific relationship between capacitance and contact area is shown in Formula 1-2:

[0063]

[0064] Where C top ——microstructure interface capacitance; C bottom —— Planar interface capacitance;

[0065] A top ——microstructure ionization contact area; A bottom ——Plane ionizing contact area.

[0066] Since the plane ionization contact area is full contact, A bottom The value of is fixed and much larger than A top The value of This term can be ignored. That is, the total capacitance of the ionization pressure sensor can be simplified to C tota l≈C top ∝A top , the measured capacitance is proportional to the contact area at the top. The linear response is further controlled by converting material properties into structural control. Therefore, in order to achieve the linear response of the ionization pressure sensor, the microstructure of the sensing functional material needs to be designed to ensure that the contact area between the material functional layer and the electrode layer increases linearly with the increase of pressure.

[0067] (III) Design of linear microstructure of sensing material layer:

[0068] First, in order to ensure the universality of this regulation method, P(EA-co-AN) ion gel was taken as the research object, so as to facilitate the subsequent regulation of the coordination between its mechanical properties and linear structure.

[0069] The specific preparation method of the P(EA-co-AN) ion gel used is:

[0070] (1) Add a photoinitiator (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, a crosslinker trimethylolpropane trimethacrylate, an ionic liquid 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, an acrylonitrile monomer and an ethyl acrylate monomer to a brown reagent bottle in sequence, and shake the mixture to obtain a clear solution, which is an ionic liquid precursor; wherein the mass ratio of the ethyl acrylate monomer to the acrylonitrile monomer is 4:6, the mass ratio of the ionic liquid to the polymer monomer is 1:1, the mass ratio of the crosslinker to the polymer monomer is 0.1:1, and the mass ratio of the photoinitiator to the polymer monomer is 0.005:1.

[0071] (2) bonding polyethylene (PE) release films to two glass sheets respectively, placing silicone gaskets around the two glass sheets with the PE release films on the surfaces thereof, and dripping the prepared clear liquid into the gap between them;

[0072] (3) Place the glass plate rich in ionic liquid precursor into a UV curing box and cure at a wavelength of 365 nm with a power density of 600 mj / cm at 8 watts. 2 The ion gel was cured for 60 minutes under the conditions of 400 μm and the cured ion gel was placed in a fume hood for 12 hours to volatilize the unreacted monomers, thereby completing the preparation of the ion gel layer with a thickness of 120 μm.

[0073] Secondly, the simulation data is based on its mechanical data. The Ogden model is also one of the common models for describing uniaxial tension, and is often used to predict the mechanical behavior of elastic bodies. Therefore, it is set as the subsequent simulation model. In the process of uniaxial tension, the basic expression of the Ogden model is:

[0074]

[0075] Where: N is the order of the model; μ i and α i is the constant of the material; λ is the principal elongation of the strain tensor. Each parameter is obtained from the tensile curve fitting result. The Ogden elastic model in Abaqus is used to fit the measured curve, as shown in the following figure. Figure 3 As shown, it can be seen that the two are basically consistent.

[0076] Furthermore, in order to simplify the design difficulty of the linear microstructure, a columnar microstructure is selected as the seed model for parameter adjustment. Its "sideways" columnar structure can also enhance the structural stability of the entire device during the recompression process. The columnar microstructure specifically contains five dimensions: the height of the column (h), the horizontal radius of the two sides (x1, x2) and the vertical radius (y1, y2), and the height of the column will be determined as x1, x2, y1, y2 are determined, as shown in the following example: Figure 4As shown. It is expected that the contact area between the microstructures and the plane will increase rapidly as the height decreases, compensating for the linear gap between the contact area and the pressure.

[0077] Furthermore, considering the limitations of the dimensions of the microstructures and the preparation accuracy of 3D printing, the lower limit of each dimension is set to be not less than 10 μm, and the upper limit is set to be not more than 100 μm to shrink the boundary range of the operation. Similarly, the internal constraint conditions of x2 > x1 and y2 < y1 are specified to further tighten the boundary, reduce the calculation cost and the design difficulty, and it is expected to control the total data volume within the order of dozens of times.

[0078] Furthermore, when pressure is applied, the longitudinal deformation of the microstructures is directly related to the contact area. When the height of the column is too high, "collapse" of the structure will occur during deformation, resulting in a non-linear contact area-pressure response relationship. Therefore, it is particularly important to select an appropriate aspect ratio of the microstructures. Based on this, the experimental simulation of the variation relationship between the contact area and the pressure under different aspect ratio models is carried out to explore a sample with an appropriate aspect ratio that can achieve area compensation and thus achieve linearity. The simulation results show that when the aspect ratio of the material is set to be less than 4 (satisfying 4x1 ≥ y1), the collapse of the structure during compression can be avoided, as specifically shown in Figure 5 As shown, that is, the deformation direction of the column-like microstructures is not parallel to the pressure direction, resulting in side bending and other situations, increasing the complexity of the calculation.

[0079] Based on this, the experiment sets x1 = 25 μm, satisfying the condition of 4x1 ≥ y1, that is, when y1 = 100 μm, the other two parameters are adjusted and set. The simulation results show that when there is a certain height difference between the head and the tail of the structure, the area compensation effect is obvious under high pressure. Therefore, the size of y2 is limited within 0 - 20 μm, and the linearity of different sizes of x2 is simulated and judged. By continuously adjusting the sizes of x2 and y2 through the bisection method, after hundreds of simulation results, the sizes of each part of the microstructures are finally determined: x1 = 25 μm, y1 = 100 μm, x2 = 65 μm, y1 = 10.2 μm, and its specific morphology diagram is as shown in Figure 6 Figure a. The linearity of the simulated pressure - contact area output curve of the microstructures can reach 0.994, as shown in Figure 6 Figure b, which is much higher than the current linearity index of the sensors.

[0080] (IV) Construction of a sensing material layer with a linear microstructure:

[0081] Export the linear microstructures obtained in step (three) and realize the virtual microstructures through a high-precision 3D printer. The model of the precision 3D printer used in the present invention is the BMF S130 type (digital light processing type), and the specific preparation method includes the following steps:

[0082] Step 1: Pre-processing of linear microstructures. The calculated 3D linear microstructure array model is imported into MaterialiseMagics software for model defect inspection and repair to reduce the memory size of the model and obtain an STL format model suitable for slicing. The sliced ​​model is then imported into the print slicing tool (BMF-3Dslicer) for slicing, where the platform accuracy is 2μm, the layer thickness is 5μm, and the total area of ​​3D printing is controlled within 38.4mm·21.6mm.

[0083] Step 2: 3D printing parameter setting and printing process. The 3D printing platform and the fixture are leveled so that the horizontal deviation around them does not exceed 5μm. Then the model sliced ​​by the slicing tool is imported into the 3D printer, and the corresponding printing parameters are set according to different structures. After the parameters are set successfully, the printer automatically prints according to the set parameters. Among them, the 3D printing material used is the 3D printer's matching resin, that is, the light-curing resin model is BMF-HTL-yellow.

[0084] Step 3: Remove the mold and clean it. After the printing is completed, take out the resin material and put it into ethanol and deionized water for 30 minutes to remove the precursor remaining in the cured template. After the ultrasonic resin material is placed in a 50°C oven for 2 hours, the resin mold is obtained.

[0085] Step 4: Bond a polyethylene (PE) release film to one glass sheet and a printed resin microstructure mold to the other glass sheet. Place silicone gaskets around the two glass sheets and pour in the ionic liquid precursor prepared in step (1) of step (3).

[0086] The mold containing the ionic liquid precursor was placed in a UV curing box and cured at a wavelength of 365 nm with a power density of 600 mj / cm at 8 watts. 2 The cured ion gel was taken out and placed in a fume hood for 12 hours to volatilize the unreacted monomers, thereby obtaining a sensing material with an orderly distributed linear microstructure on the surface, with a thickness of 120 μm.

[0087] The surface morphology of the obtained sensing material was observed by scanning electron microscopy (SEM). Figure 7 As shown in the figure, it can be seen that the linear microstructure on the surface of the material has been successfully constructed, and its microstructure is composed of multiple special-shaped units staggered in rows, each of which has a head with a semicircular cross-section and a tail that is flattened and extends backward along the head.

[0088] (V) Investigating the influence of Young's modulus of ion gel on the sensitivity and linear range of the prepared sensor

[0089] By adjusting the amount of the cross-linking agent in the fourth step of the ionic liquid precursor in step (iv), sensing material layers with different Young's moduli are prepared and respectively prepared as sensors for relevant response curve testing.

[0090] First, sensing materials with different cross-linking ratios were prepared and subjected to stress-strain tests using a tensile testing machine. It was found that by increasing the cross-linking density of the gel under the condition of a fixed monomer ratio, its modulus could be significantly increased without reducing the strength of the material. The strength of the ion gel was increased by 4 MPa while the modulus was increased by 2 orders of magnitude. Figure 8 As shown. The higher the proportion of the cross-linking agent, the higher the cross-linking density between the polymer chains, the higher the Young's modulus of the ion gel material, the harder the material becomes, and the slower the contact area changes with pressure. This greatly broadens the linear range of the sensor, making it possible for the linear acquisition of the gel sensing material layer in high-pressure scenarios.

[0091] Secondly, the sensitivity of the sensor material layer was tested under the same test conditions using a compression fatigue tester. The results showed that with the increase of the cross-linking ratio, the linear range of the sensor was significantly widened, but this was accompanied by a significant decrease in sensitivity. The two showed a contradictory relationship, such as Fig. 9 shown.

[0092] At the same time, the simulation software was used to simulate the changes in the contact area between the electrode and the ion gel material of four different Young's moduli under the same pressure test conditions. Due to the high modulus of the gel material, the contact area between the electrode and the ion gel material changes less under the same pressure test conditions, which naturally leads to lower sensitivity and a wider linear pressure response range. The data generated by the simulation is consistent with the conclusions obtained from the test.

[0093] Although the increase in Young's modulus of the ion gel sensing material layer will cause a significant decrease in the sensitivity of the sensor while widening the linear response range of the sensor, the electrode material (PI / Cu composite film) and the ion gel functional material will form an EDL at the interface, resulting in an extremely high capacitance per unit area. This also makes the prepared sensor have an ultra-wide range and high linearity while having a sensitivity far higher than other capacitive sensors. Compared with traditional capacitive sensors, the sensitivity is at least three orders of magnitude higher and can still detect weak physiological signals, such as finger pulses.

[0094] In summary, in the prior art, usually increasing the sensitivity will lead to a narrowing of the sensor range. The reason is that the high-sensitivity design is usually optimized for small changes. When the input signal exceeds a certain range, the mismatch between the pressure increment generated by the sensor and the electrical signal leads to signal saturation under high pressure, making it difficult to ensure accurate measurement under a wide range, thereby hindering the realization of the linear response of the sensor under the full range. The present invention, by designing a linear microstructure and regulating ion gel functional materials, combines 3D printing technology and ionic liquid reverse molding technology to prepare functional materials with complex structures in an integrated manner, thereby solving the key problem that the current sensor's high sensitivity, high linearity and wide range of sensing performance cannot be achieved at the same time. The prepared sensor can achieve ultra-sensitive, high linearity and wide range with a linearity higher than 0.997 within 0-2MPa, which is much higher than all sensors currently on the market, and has the world's leading sensing performance. The prepared flexible pressure sensor with high sensitivity, high linearity and wide range can be widely used in many technical fields such as health monitoring, wearable devices, robot tactile, virtual reality, etc.

[0095] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for synergistically enhancing the sensing performance of a sensor by utilizing microstructure design and material regulation, characterized in that: The following steps are involved: S1 fits the stress-strain curve of the ion gel with the Ogden model, takes the columnar microstructure as the seed model for parameter adjustment, performs microstructure design simulation, and obtains a linear microstructure array model; S2 exports the obtained microstructure model, automatically prints a resin mold through a 3D printer, pours the ionic liquid precursor into the obtained mold, and demolds it after curing to obtain a sensing material with an orderly distributed linear microstructure on the surface; S3 uses the obtained sensing material as an intermediate ion functional layer to assemble an ion-type flexible pressure sensor.

2. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 1, characterized in that: In step S2, the preparation method of the ionic liquid precursor includes the following steps: uniformly mixing the polymer monomer, the ionic liquid, the crosslinking agent and the initiator to obtain; wherein the mass ratio of the crosslinking agent to the polymer monomer is (0.05-0.3):

1.

3. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 1, characterized in that: In step S2, the surface microstructure of the prepared sensing material is specifically composed of a plurality of special-shaped units arranged in a staggered manner head to tail, each of which has a head with a semicircular cross-section and a tail that is flattened and extends backward along the head.

4. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 1, characterized in that: In step S3, the prepared ionization-type flexible pressure sensor can achieve a linearity higher than 0.997 within 0-2MPa.

5. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 1, characterized in that: In step S1, the columnar microstructure includes a columnar height (h), horizontal radii (x1, x2) of the head and tail sides, and vertical radii (y1, y2) of the head and tail sides.

6. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 5, characterized in that: In step S1, the constraint conditions of the columnar microstructure include: the lower limit of each size is not less than 10 μm, the upper limit is not more than 100 μm, x2>x1, y2 <y1。 7. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 6, characterized in that: In step S1 , the microstructure is designed and simulated, and the simulation results are: x1=25 μm, y1=100 μm, x2=65 μm, y1=10.2 μm.

8. The method for realizing synergistic enhancement of sensor performance by utilizing microstructure design and material regulation as claimed in claim 1, characterized in that: Step S2 specifically includes: S21 uses software to check, repair and slice the calculated linear microstructure array model; S22 imports the sliced ​​model into a 3D printer for automatic printing to obtain a resin mold; S23 takes out the resin mold and cleans it; S24: pouring the ionic liquid precursor into the cleaned mold, and removing the mold after curing.

9. A flexible pressure sensor having high sensitivity, high linearity and wide range, prepared by the method as described in any one of claims 1 to 8.

10. Application of the flexible pressure sensor having high sensitivity, high linearity and wide range prepared by the method as described in any one of claims 1 to 8 in the fields of health monitoring, wearable devices, robot touch and virtual reality.

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