Temperature-pressure self-decoupled flexible sensor based on microstructured ionic materials

Abstract

The application discloses a temperature-pressure self-decoupling flexible sensor based on microstructure ionic materials. The sensor is composed of a top layer structure, a microstructure layer and a substrate layer arranged in sequence from top to bottom, the upper surface of an ionic gel array in the top layer structure is in contact with a flexible electrode array, the lower surface of the ionic gel array in the microstructure layer is in contact with a microstructure ionic gel thin layer, the microstructure ionic gel thin layer and a conductive metal thin layer are arranged in sequence from top to bottom, the conductive metal thin layer is electrically connected with a signal output interface, the flexible electrode array, the ionic gel array, the microstructure ionic gel thin layer and the conductive metal thin layer constitute a capacitive pressure sensor, and the flexible electrode array, the ionic gel array and the microstructure ionic gel thin layer constitute a resistance temperature sensor. The multi-mode flexible sensor disclosed by the application can simultaneously detect three sensing modes of temperature, pressure and proximity, the temperature and proximity sensing modes are realized through part of the structure in the pressure sensing mode, the integrated degree is high, and the space is compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a temperature-pressure self-decoupling multi-modal flexible sensor based on micro-structured ionic materials. BACKGROUND

[0002] Human skin is soft, self-repairing, and can perceive subtle environmental differences, such as a breeze, which has stimulated a large amount of research on artificial skin-like materials. When a machine performs intelligent grasping work, it is necessary to accurately judge the grasping force to ensure that the work is completed without damaging the target.

[0003] An ionic gel is a solid mixture with ionic conductivity, usually composed of a high-molecular-weight organic polymer and a salt electrolyte material that can be ionized. The polymer molecular chains are interconnected or entangled, forming a spatial network structure, and the structure voids are filled with anions and cations as dispersion media, similar to the structure of traditional gels, hence the name "ionic gel". The high-molecular-weight polymers that make up the ionic gel are mostly gel-like block copolymers, which form a cross-linked network structure, providing the ionic gel with high tensile strength, and the network structure also provides a channel for ion movement. The ionic liquid mixed in the high-molecular-weight copolymer is a molten strong electrolyte. This strong electrolyte exists in the ionic gel in the form of anions and cations in a molten state. Because the functional groups of the copolymer have many coordination sites, under the condition of no external electric field, the anions and cations are mostly connected to the functional groups of the copolymer by coordination bonds and dispersed throughout the ionic gel. Under the action of an external electric field, the local movement of ions between the polymer chains and the ion coordination sites produces the migration of anions and cations, resulting in a non-uniform charge distribution in the ionic gel, with anions and cations stacked on both ends of the interface, forming a double electric layer.

[0004] Temperature also changes the distribution of ions. As the temperature rises, the number of ions increases because more ions will be released from the polymer network. In addition, as the temperature rises, ions will gain more energy, so the movement speed of ions will be faster. When a potential difference is applied to the ionic material, more ions will move to the electrode surface (i.e., the degree of polarization is higher). Due to the existence of these two phenomena, the capacitance will increase with the increase of temperature. Therefore, when testing the pressure generated by an object with temperature using the electric double layer effect, the change in temperature caused by the contact will change the measured capacitance, resulting in an error in the measured pressure. Therefore, it is necessary to decouple the dual effects of temperature and pressure, eliminate the change in capacitance caused by temperature changes, and accurately measure the pressure. SUMMARY

[0005] In order to solve the problem that temperature changes caused by contact during testing pressure by using the electric double layer effect, and then change the measured capacitance, cause the error of the measured pressure, and realize the function of proximity sensing, the application provides a temperature-pressure self-decoupling flexible sensor based on micro-structured ionic material.

[0006] The technical scheme adopted by the application is:

[0007] The sensor is composed of a top layer structure, a micro-structured layer and a substrate layer arranged in sequence from top to bottom, the top layer structure is provided with a lead-out belt, the lead-out belt is bonded on the substrate layer, so that a pre-pressure is generated between the top layer structure and the micro-structured layer;

[0008] The top layer structure includes a flexible electrode array and an ionic gel array, the upper surface of the ionic gel array is in contact with the flexible electrode array, wherein each ionic gel unit in the ionic gel array completely covers the corresponding flexible electrode unit in the flexible electrode array; the lower surface of the ionic gel array is in contact with the upper surface of the micro-structured layer;

[0009] The micro-structured layer includes a micro-structured ionic gel thin layer, a conductive metal thin layer and a signal output interface, the lower surface of the ionic gel array is in contact with the upper surface of the micro-structured ionic gel thin layer, the micro-structured ionic gel thin layer and the conductive metal thin layer are arranged in sequence from top to bottom, the conductive metal thin layer is electrically connected with the signal output interface, and the conductive metal thin layer is arranged on the substrate layer;

[0010] The flexible electrode array, the ionic gel array, the micro-structured ionic gel thin layer and the conductive metal thin layer constitute a capacitive pressure sensor, wherein the flexible electrode array and the conductive metal thin layer serve as two electrode plates of the capacitive pressure sensor, and the ionic gel array and the micro-structured ionic gel thin layer serve as a dielectric layer of the capacitive pressure sensor;

[0011] The flexible electrode array and the ionic gel array constitute a resistance temperature sensor, the flexible electrode array serves as an electrode of the resistance temperature sensor, and the ionic gel array serves as a conductive medium of the resistance temperature sensor.

[0012] The flexible electrode array is composed of a plurality of flexible electrode units arranged in an N*M array, each electrode unit has the same structure and includes a center disc electrode and a semi-closed ring electrode, the center disc electrode is placed in the ring electrode, and the center disc electrode and the ring electrode are arranged with a spacing therebetween.

[0013] The substrate layer is a flexible PI film.

[0014] The ion gel array is composed of a plurality of ion gel units arranged in an N x M array; the mass ratio of each component material in the ion gel array is dimethylacetamide DMAC: thermoplastic polyurethane elastomer TPU: ionic liquid IL = 8:1:1 to 12:1:1.

[0015] The microstructured ion gel thin layer is provided with an array of microprotrusions on the side in contact with the ion gel array, and the side in contact with the conductive metal thin layer is smooth.

[0016] The mass ratio of each component material in the microstructured ion gel thin layer is dimethylacetamide DMAC: thermoplastic polyurethane elastomer TPU: ionic liquid IL = 10:1:1.

[0017] The conductive metal thin layer is made of copper foil.

[0018] The preparation method of the ion gel solution of the ion gel array is as follows:

[0019] First, dimethylacetamide DMAC is added as a solvent in a beaker, followed by the addition of thermoplastic polyurethane elastomer TPU and [EMIM][TFSi] ionic liquid, and the mass ratio of the three is 10:1:1; stir for 12 hours on a magnetic stirrer to mix the three uniformly; place the ion gel solution after stirring in a vacuum defoaming machine for 20 minutes to remove the air bubbles in the ion gel solution; heat the defoamed solution at 70°C for 10 minutes to remove the water in the solution and obtain the ion gel solution;

[0020] The top layer structure is prepared by the following method:

[0021] Pour the A and B glue of the aliphatic aromatic random copolyester Ecoflex into a container, mix uniformly, and then vacuumize; pour the mixed Ecoflex solution into a mold, heat at 60°C for 2 hours to prepare a partitioning and curing mold, place the partitioning and curing mold on the flexible electrode array, with each flexible electrode unit corresponding to a space in the mold to ensure that the mold is in close contact with the flexible electrode array without gaps; use a pipette gun to drop 20ul of ion gel solution into the space in the mold; heat at 60°C for 24h to cure and form a 100um thick ion gel array, thereby obtaining the top layer structure.

[0022] The microstructured layer is prepared by the following method:

[0023] In a container, pour A, B glue of aliphatic aromatic random copolyester Ecoflex, mix evenly, and then vacuumize; use a doctor blade to coat the mixed Ecoflex solution with a thickness of 2 mm on the surface of a sandpaper with a preset mesh, and heat at 60 DEG C for 2 h to solidify; remove the sandpaper to obtain a silica gel mold with a microstructure; coat an ionic gel solution with a thickness of 3 mm on the silica gel mold; heat at 60 DEG C for 24 h to solidify, and form a microstructure ionic gel thin layer with a thickness of 300 um; and adsorb the microstructure ionic gel thin layer on a conductive metal thin layer to obtain the microstructure layer.

[0024] The present application has the following beneficial effects:

[0025] When measuring the pressure generated by an object with a temperature, the present application can measure the temperature by the resistance measured by the top layer structure, and measure the combined influence of temperature and pressure by the capacitance change, deduce the pressure on the sensor, realize the self-decoupling of temperature and pressure, accurately measure the pressure and temperature, and have great application prospects in artificial skin, robot intelligent grabbing and the like.

[0026] The present application has the function of proximity sensing, can measure the proximity of an object by the change of the capacitance value, and can position the relative position of a mechanical claw and a target when realizing the intelligent grabbing work of a robot.

[0027] The present application simulates the compliance characteristics and multi-modal sensing function of the skin of a living body, can independently measure a plurality of variables in the human-machine interaction process, reuses the same layer of electrodes to a plurality of sensing functions, simplifies the number of layers of the sensor device, optimizes the thickness of each layer, ensures the overall thickness to be 500 um, realizes the characteristics of lightness and thinness, and maximally reduces the limitation of the robot skin on the activity of a robot.

[0028] The present application uses a microstructure ionic gel, and the sensor has high sensitivity and linearity in the sensing function of pressure.

[0029] The present application has simple processing technology, all steps can be accurately quantified, the mold can be repeatedly used, and the manufacturing repeatability of equipment is good.

[0030] The present application has integrated a signal output port, and can be quickly integrated to the surface of a robot body, an end effector, an intelligent artificial limb hand and the like. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 FIG. 1 is an exploded view of the structure of the ionic gel sensor of the present application;

[0032] Figure 2 FIG. 2 is a structure diagram of the ionic gel sensor of the present application

[0033] Figure 3The top layer structure circuit diagram;

[0034] Figure 4 The circuit principle of the present application;

[0035] Figure 5 The preparation flow of the top layer structure;

[0036] Figure 6 The preparation flow of the microstructure layer;

[0037] Figure 7 The separation solidification mold;

[0038] Figure 8 The pressure cycle applied on the ionic gel;

[0039] Figure 9 The corresponding resistance change of the ionic gel;

[0040] Figure 10 The temperature-resistance calibration curve;

[0041] Figure 11 The temperature-capacitance calibration curve;

[0042] Figure 12 The pressure-capacitance calibration curve.

[0043] In the figure: top layer structure 1, microstructure layer 2, base layer 3, flexible electrode array 4, ionic gel array 5, microstructure ionic gel thin layer 6, conductive metal thin layer 7, signal output interface 8, center disc type electrode 41, circular ring type electrode 42, separation solidification mold 9. DETAILED DESCRIPTION

[0044] The present application is further described below in conjunction with the accompanying drawings.

[0045] As shown in Figure 1 and Figure 2 , the present application is composed of top layer structure 1, microstructure layer 2 and base layer 3 arranged in turn from top to bottom, the top layer structure 1 (i.e. flexible electrode array 4) is provided with a lead-out belt, the lead-out belt is bonded on the base layer 3, so that a pre-pressure is generated between the top layer structure 1 and the microstructure layer 2, and higher sensitivity is achieved; the top layer structure is used for detecting the temperature of the contact point, and it is necessary to avoid the influence of pressure on the material resistance as much as possible. Since it is necessary to test the capacitance by using the electric double layer effect, the contact resistance between the top layer structure and the microstructure layer is inevitable. By controlling the ion concentration of the ionic gel, the sheet resistance can be improved, so as to reduce the contact resistance effect. The base layer 3 is cut into shape by a flexible PI film, so as to ensure the flexibility of the sensor.

[0046] The top layer structure 1 includes a flexible electrode array 4 and a smooth ion gel array 5, the upper surface of the ion gel array 5 is arranged opposite to the flexible electrode array 4 and in close contact, wherein each ion gel unit in the ion gel array 5 completely covers the corresponding flexible electrode unit in the flexible electrode array 4; the lower surface of the ion gel array 5 is in close contact with the upper surface of the microstructure layer 2;

[0047] The microstructure layer 2 includes a microstructure ion gel thin layer 6, a conductive metal thin layer 7 and a signal output interface 8, the lower surface of the ion gel array 5 is in close contact with the upper surface of the microstructure ion gel thin layer 6, the microstructure ion gel thin layer 6 and the conductive metal thin layer 7 are arranged in a top-to-bottom manner, the conductive metal thin layer 7 is electrically connected with the signal output interface 8, and the conductive metal thin layer 7 is arranged on the base layer 3;

[0048] The microstructure layer is combined with the top layer structure, and the two layers of ion gels are in contact with each other to generate an electric double layer effect. When the two polymers are in contact with each other and a potential difference is applied on the two layers, the ions will be redistributed according to their polarity. The electric field is formed by the joint action of positive ions and negative ions. As the contact area increases, the capacitance also increases due to the increase of the electric field. The microstructure ion gel thin layer is smooth on one side and has a microstructure prepared by sandpaper on the other side. After the mesh number of the sandpaper is determined, a microstructure with good consistency can be prepared, and the sensor has good repeatability. Due to the consistency and uniformity of the microstructure prepared by the sandpaper on the macro level, as the pressure increases in the process of the sensor being pressed, the contact area of the two layers of ion gels will uniformly increase, and the sensor has high sensitivity and linearity. The thickness of the microstructure ion gel thin layer needs to be ensured to completely cover the microstructure on the sandpaper, but does not affect the capacitance and resistance characteristics of the sensor, and can be as small as 300 um.

[0049] The flexible electrode array 4, the ion gel array 5, the microstructure ion gel thin layer 6 and the conductive metal thin layer 7 constitute a capacitive pressure sensor, wherein the flexible electrode array 4 and the conductive metal thin layer 7 serve as the capacitive pressure sensor, wherein the center disc type electrode 41 in each flexible electrode unit in the flexible electrode array, the ion gel unit attached thereto, the microstructure ion gel thin layer and the conductive metal thin layer can be regarded as a capacitive pressure sensing unit, and the capacitance signal of the capacitive pressure sensing unit is led out by the center disc type electrode 41 and the conductive metal thin layer. The flexible electrode array 4 and the conductive metal thin layer 7 respectively serve as two electrode plates of the capacitive pressure sensor which are parallel to each other, the ion gel array 5 and the microstructure ion gel thin layer 6 serve as a dielectric layer of the capacitive pressure sensor, and the conductive metal thin layer 7 can sense the approach of external conductive objects by measuring the change of the capacitance to ground when the conductor approaches, and the measurement of the capacitance of the capacitive pressure sensor reflects the magnitude and distribution of the pressure applied by the external environment;

[0050] The flexible electrode array 4 and the ionic gel array 5 constitute a resistance temperature sensor, and the temperature change is detected by the resistance change. Each flexible electrode unit and the ionic gel unit attached thereto can be regarded as a resistance temperature sensor, and the resistance signal is jointly led out by the center wafer-shaped electrode 41 and the semi-closed ring-shaped electrode 42; the flexible electrode array 4 serves as the electrode of the resistance temperature sensor, and the ionic gel array 5 serves as the conductive medium of the resistance temperature sensor.

[0051] In the temperature sensing module, the resistance of the ionic gel of the corresponding detection point is measured by the center wafer-shaped electrode and the ring-shaped electrode, and the temperature of the detection point can be calculated; in the pressure sensing module, the center wafer-shaped electrode serves as one pole of the capacitance measurement; for a flat plate capacitor, the electric field strength between the two flat plates determines the size of the capacitor, and the electrode area determines the electric field strength, so that the use of a larger center wafer-shaped electrode can improve the sensitivity of the sensor. The ionic gel needs to be configured in proportion. Adding more ionic liquid in the sample can enhance the electric double layer effect, thereby improving the sensitivity of the sensor, but it will affect the mechanical properties and transparency of the sample. Therefore, a trade-off between electrical performance and mechanical performance is required.

[0052] In summary, the multi-modal flexible sensor disclosed by the application can simultaneously detect three sensing modes of temperature, pressure and proximity, and the temperature and proximity sensing modes are realized by part of the structure in the pressure sensing mode, so that the sensor has high integration and compact space.

[0053] The multi-modal flexible sensor disclosed by the application utilizes the characteristic that the resistance value of the ionic material itself is not sensitive to external force, decouples the double influence of temperature and pressure on the capacitance value in the capacitive pressure sensing mode, excludes the capacitance change caused by temperature change, and accurately measures the pressure applied to the sensor. When measuring the pressure generated by an object with temperature, the multi-point temperature distribution can be calculated by the resistance of the ionic gel array in the top layer structure, the relationship curve between temperature, capacitance change and pressure can be measured by calibrating the capacitance change in the pressure sensing mode, the pressure on the sensor can be derived according to the temperature value calculated by the resistance, the self-decoupling of temperature and pressure is realized, the pressure and temperature are accurately measured, the decoupling process only involves the ionic material of the capacitive pressure sensor itself, without other materials, and without the need to set other temperature sensors outside the sensor, realizing the self-decoupling of the ionic material and the self-decoupling of the sensor device. Through the design of the signal acquisition circuit, when the proximity sensing module is used, the center wafer-shaped electrodes on the flexible electrode array can be connected in series to form a larger ground capacitance; the capacitance value change caused by the proximity of the object can be used to measure the proximity of the object.

[0054] As Figure 3As shown, the flexible electrode array 4 is composed of a plurality of flexible electrode units arranged in an N x M array, each electrode unit having the same structure and including a center disc electrode 41 and a semi-enclosed ring electrode 42, the ring electrode 42 having the center disc electrode 41 placed therein and being arranged at intervals with the center disc electrode 41. Figure 3 and Figure 4 The signal output port 1_0 of the ring electrode 42 is connected in series, and the signal output port 1_1-1_9 of the center disc electrode 41 is independently outputted. Figure 3 and Figure 4 The resistance between each group of electrodes can be measured through the signal output port 1_0 and the signal output port 1_1-1_9, and the temperature of the contact point can be obtained by comparing with the calibration results. The capacitance between each group of electrodes can be measured through the signal output interface 8 and the signal output port 1_1-1_9, and the results under the combined influence of temperature and pressure can be obtained by comparing with the calibration results. Through self-decoupling calculation, the pressure on the contact point can be obtained. Thus, the simultaneous measurement of the temperature and pressure of the contact point is realized. In the temperature sensing module, the resistance of the ion gel at the corresponding detection point is measured through each center disc electrode 41 and ring electrode 42, so as to calculate the temperature of the detection point; in the pressure sensing module, the center disc electrode 41 serves as one pole for capacitance measurement; for a flat plate capacitor, the electric field strength between the two flat plates determines the size of the capacitor, and the electrode area determines the electric field strength, so that the use of the center disc electrode 41 can improve the sensitivity of the sensor.

[0055] The substrate layer 3 is a flexible PI film with a thickness of 50 μm, which helps to reduce the overall thickness of the sensor and is conducive to the application in robot intelligent grabbing, artificial skin and other aspects.

[0056] The ion gel array 5 is composed of a plurality of ion gel units arranged in an NXM array; the thickness of the ion gel array 5 does not affect the capacitance and resistance performance of the sensor, and the thickness of the gel can be minimized to about 100 um under the premise of ensuring complete coverage of the electrode; there is no contact between the ion gel units of the ion gel array 5, which are mutually insulated and independently provide data during operation; the resistance of the ion gel array 5 is not sensitive to pressure; in the temperature sensing module, the resistance value of the ion gel can be measured to calculate the temperature of the ion gel unit; in the pressure sensing module, the ion gel array 5 serves as one layer of the electric double layer structure; the ion gel used in the ion gel array 5 requires an organic solvent, including dimethylacetamide DMAC; an elastic polymer, including thermoplastic polyurethane elastomer TPU; and an ionic liquid IL, including [EMIM][TFSi]; the mass ratio of the components in the ion gel array 5 is dimethylacetamide DMAC: thermoplastic polyurethane elastomer TPU: ionic liquid IL = 8:1:1 to 12:1:1. The solution prepared has a low viscosity to meet the requirements of subsequent operations.

[0057] The microstructured ion gel thin layer 6 has a microstructured array on the side in contact with the ion gel array 5; in specific implementations, the microstructure is prepared using sandpaper; after the grit size of the sandpaper is determined, a microstructure with good consistency can be prepared, and the sensor has good repeatability; due to the consistency and uniformity of the microstructure prepared using sandpaper, during the pressure sensing process, as the pressure increases, the contact area between the two layers of ion gel increases uniformly, thereby increasing the sensitivity and linearity of the capacitive pressure sensor. The side of the microstructured ion gel thin layer 6 in contact with the conductive metal thin layer 7 is smooth; the thickness of the microstructured ion gel thin layer 6 needs to ensure complete coverage of the microstructure on the sandpaper, but does not affect the capacitance and resistance characteristics of the sensor, and can be as small as 300 um; the microstructured ion gel thin layer 6 serves as one layer of the electric double layer in the pressure sensing module; the capacitance of the electric double layer depends on the contact area; during the pressure sensing process, the microstructured ion gel thin layer 6 deforms, increasing the contact area with the ion gel array 5, thereby increasing the capacitance of the sensor;

[0058] The ion gel used in the microstructured ion gel thin layer 6 requires an organic solvent, including dimethylacetamide DMAC; an elastic polymer, including thermoplastic polyurethane elastomer TPU; and an ionic liquid, including [EMIM][TFSi]; the mass ratio of the components in the microstructured ion gel thin layer 6 is dimethylacetamide DMAC: thermoplastic polyurethane elastomer TPU: ionic liquid IL = 10:1:1.

[0059] The conductive metal thin layer 7 is made of copper foil, usually tens of microns thick, serving as one pole in the parallel-plate capacitor, helping to reduce the overall thickness of the sensor; the glue side of the conductive metal thin layer 7 is adhered to the base layer 3, ensuring stable adhesion and fixing the relative positions between the layers during the compression of the sensor; the metal side of the conductive metal thin layer 7 is adhered to the microstructure ionogel thin layer 6 through the adhesion of the ionogel itself; the conductive metal thin layer 7 has high fatigue resistance and flexibility, and can maintain stable performance during long-term use.

[0060] The preparation method of the ionogel solution of the ionogel array 5 is as follows:

[0061] First, add dimethylacetamide (DMAC) as a solvent to a clean and dry beaker, then add thermoplastic polyurethane elastomer (TPU) and [EMIM][TFSi] ionic liquid, with a mass ratio of 10:1:1; stir for 12 hours on a magnetic stirrer to mix the three uniformly; then place the ionogel solution after stirring in a vacuum defoaming machine for 20 minutes to remove air bubbles in the ionogel solution; heat the defoamed solution at 70°C for 10 minutes to remove water in the solution; pour the solution into a dry and clean glass container and seal it for storage to obtain the ionogel solution; adding more ionic liquid in the sample can increase the number of free ions in unit volume, thereby improving the sensitivity of the sensor, but it will affect the mechanical properties and transparency of the sample; therefore, a trade-off between electrical performance and mechanical performance needs to be made according to the requirements of the application scenario; the ionogel used for the microstructure ionogel thin layer needs an organic solvent, including dimethylacetamide (DMAC); it needs an elastic polymer, including thermoplastic polyurethane elastomer (TPU); it needs ionic liquid (IL), including [EMIM][TFSi]; the mass ratio during configuration is DMAC:TPU:IL=10:1:1. The prepared solution has a certain viscosity to meet the requirements of subsequent operations.

[0062] As shown in Figure 5 The top layer structure 1 is prepared by the following method:

[0063] Pour the A and B glue of aliphatic aromatic random copolyester Ecoflex into a container, mix well, and then vacuumize; pour the mixed Ecoflex solution into a mold, heat at 60°C for 2 hours, and prepare the partitioning and curing mold 9, as shown in Figure 6As shown, the partitioning and curing mold 9 is carefully placed on the flexible electrode array 4, with each flexible electrode unit corresponding to the space on the mold, ensuring that the mold is attached to the flexible electrode array 4 without gaps; 20ul of ion gel solution is dropped into the space in the mold using a pipette; heated at 60°C for 24h to cure, forming a 100um thick ion gel array 5; the partitioning and curing mold is carefully removed, obtaining the top layer structure 1; the partitioning and curing mold 9 can be reused, and all steps can be accurately quantified to ensure good repeatability of equipment manufacturing.

[0064] As shown, the microstructure layer 2 is prepared by the following method: Figure 6

[0065] The A and B glue of the aliphatic aromatic random copolyester Ecoflex is poured into a container and mixed uniformly, then vacuumized; a 2mm thick mixed Ecoflex solution is scraped on the surface of a pre-set mesh sandpaper using a scraper, and heated at 60°C for 2h to cure; the sandpaper is removed to obtain a silicone mold with microstructure; a 3mm thick ion gel solution is scraped on the silicone mold; heated at 60°C for 24h to cure, forming a 300um thick microstructure ion gel thin layer 6; the microstructure ion gel thin layer 6 is adsorbed on the conductive metal thin layer 7 (the side without glue of the copper foil) using the inherent adsorption capacity of the smooth surface of the ion gel, obtaining the microstructure layer 2; the silicone mold with microstructure can be reused, and all steps can be accurately quantified to ensure the repeatability of the performance of the microstructure layer prepared each time.

[0066] The signal output interface 8 is bonded to the base layer 3 using conductive adhesive; the signal output interface 8 is wrapped using insulating tape to prevent corrosion of the electrode and changes in conductive performance caused by changes in the external environment; the conductive metal thin layer 7 is used as a common electrode for each detection point in the pressure sensing module, and the electrical signal output is measured through the signal output interface 8.

[0067] ​The sensor can utilize the characteristic that the resistance value of the ion material itself is not sensitive to external force, decouples the double influence of temperature and pressure in the decoupling pressure sensing mode, excludes the capacitance change caused by temperature change, and accurately measures the pressure applied to the sensor; when measuring the pressure generated by an object with temperature, the present application can calculate the temperature distribution of multiple points by the resistance measured by the ion gel array 5 in the top layer structure 1, calibrate the relationship curve between the capacitance and temperature and the capacitance and pressure in the pressure sensing mode, and according to the temperature value calculated by the resistance at present, further utilize the capacitance and temperature relationship curve, deduce the capacitance change caused by temperature and exclude the change, obtain the pressure suffered by the sensor, realize the self-decoupling of temperature and pressure, and accurately measure the pressure and temperature; the decoupling process only involves the ion material of the capacitive pressure sensor itself, without other materials, without the need to set other temperature sensors outside the sensor, realizing the self-decoupling of ion material and the self-decoupling of sensor device.

[0068] Through the design of the signal acquisition circuit, when the proximity sensing module is used, the center wafer-shaped electrodes 41 on the flexible electrode array 4 can be connected in series to form a larger ground capacitance, and the capacitance value change caused by the object approaching can be used to measure the object approaching; the conductive metal thin layer 7 can also be regarded as a larger electrode, and the ground capacitance value change of the electrode caused by the object approaching can be used to measure the object approaching; the center wafer-shaped electrodes 41 can also be connected in series to form a larger electrode, and the mutual capacitance value change of the electrode pair caused by the object approaching can be used to measure the object approaching.

[0069] As shown in Figure 8 , the resistance change of the ion gel corresponding to the 0-1N cycle pressure applied to the ion gel is shown in Figure 9 ; under the action of pressure cycle, the resistance change rate of the ion gel is less than 1%, which indicates that the ion gel is a material not sensitive to pressure, and the temperature of the contact point can still be accurately measured by resistance during the pressure process, ensuring the reliability and accuracy of the temperature sensing module.

[0070] As shown in Figure 10 , the resistance corresponding to the temperature change in the range of 10-60℃ is changed in the range of 2.3-0.22MΩ, and the change rate is 1000%, which can be used to calculate the temperature of the sensor detection point by combining the measured resistance with the calibration result.

[0071] As shown in Figure 11As shown, the guaranteed pressure is 2N, which can make the sensor pressure sensing module reach the maximum range. The temperature changes from 10-60℃, and the capacitance changes in the range of 580-3650pF, with a change rate of 5300%. Since the capacitance value of the electric double layer is determined by the contact area and ion concentration, and temperature changes only change the ion concentration without changing the contact area, the temperature capacitance calibration curve can be used to calculate the proportion of the change in the sensor capacitance value caused by temperature changes. Therefore, the equivalent capacitance value at 20℃ can be calculated by combining the measured temperature value.

[0072] As shown in Figure 12 At room temperature of 20℃, as the pressure increases from 0 to 0.5N, the sensor capacitance changes from 40pF to 1000pF, with a change rate of 2500%. The equivalent capacitance value calculated in the early stage can be used to calculate the size of the pressure on the sensor, and the accurate measurement of temperature and pressure can be completed.

Claims

1. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials, characterized in that, It is composed of a top structure (1), a microstructure layer (2) and a base layer (3) stacked from top to bottom. The top structure (1) is provided with a lead-out strip, which is bonded to the base layer (3) to generate pre-pressure between the top structure (1) and the microstructure layer (2). The top-level structure (1) includes a flexible electrode array (4) and an ion gel array (5). The upper surface of the ion gel array (5) is in contact with the flexible electrode array (4), wherein each ion gel unit in the ion gel array (5) completely covers the corresponding flexible electrode unit in the flexible electrode array (4); the lower surface of the ion gel array (5) is in contact with the upper surface of the microstructure layer (2). The microstructure layer (2) includes a microstructure ion gel thin layer (6), a conductive metal thin layer (7), and a signal output interface (8). The lower surface of the ion gel array (5) is in contact with the upper surface of the microstructure ion gel thin layer (6). The microstructure ion gel thin layer (6) and the conductive metal thin layer (7) are stacked from top to bottom. The conductive metal thin layer (7) is electrically connected to the signal output interface (8). The conductive metal thin layer (7) is disposed on the substrate layer (3). A flexible electrode array (4), an ion gel array (5), a microstructured ion gel thin layer (6), and a conductive metal thin layer (7) constitute a capacitive pressure sensor. The flexible electrode array (4) and the conductive metal thin layer (7) serve as the capacitive pressure sensor, and the flexible electrode array (4) and the conductive metal thin layer (7) serve as the two electrode plates of the capacitive pressure sensor, respectively. The ion gel array (5) and the microstructured ion gel thin layer (6) serve as the dielectric layer of the capacitive pressure sensor. The flexible electrode array (4) and the ion gel array (5) constitute a resistive temperature sensor; the flexible electrode array (4) serves as the electrode of the resistive temperature sensor, and the ion gel array (5) serves as the conductive medium of the resistive temperature sensor.

2. The temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The flexible electrode array (4) is composed of multiple flexible electrode units arranged in an N×M array. Each electrode unit has the same structure, including a central circular electrode (41) and a semi-enclosed annular electrode (42). The central circular electrode (41) is placed inside the annular electrode (42), and the central circular electrode (41) and the annular electrode (42) are arranged at intervals.

3. The temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The substrate layer (3) is a flexible PI film.

4. The temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The ion gel array (5) is composed of multiple ion gel units arranged in an N×M array; the mass ratio of each component material in the ion gel array (5) is between 8:1:1 and 12:1:

1.

5. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The side of the microstructured ion gel thin layer (6) that contacts the ion gel array (5) is provided with a micro-protrusion structure array, and the side of the microstructured ion gel thin layer (6) that contacts the conductive metal thin layer (7) is smooth.

6. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The mass ratio of each component material in the microstructured ionogel thin layer (6) is dimethylacetamide (DMAC): thermoplastic polyurethane elastomer (TPU): ion liquid (IL) = 10:1:

1.

7. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The conductive metal thin layer (7) is made of copper foil.

8. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 1, characterized in that, The method for preparing the ion gel solution of the ion gel array (5) is as follows: First, dimethylacetamide (DMAC) is added to a beaker as a solvent, followed by thermoplastic polyurethane elastomer (TPU) and [EMIM][TFSi] ionic liquid, with a mass ratio of 10:1:

1. The mixture is stirred on a magnetic stirrer for 12 hours to ensure homogeneity. The resulting ionic gel solution is then placed in a vacuum defoamer for 20 minutes to remove air bubbles. Finally, the defoamed solution is heated at 70°C for 10 minutes to remove water and obtain the ionic gel solution.

9. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 8, characterized in that, The top-level structure (1) is prepared by the following method: Pour the A and B adhesives of the aliphatic aromatic random copolyester Ecoflex into a container, mix them evenly, and then vacuum. Pour the mixed Ecoflex solution into a mold and heat it at 60 degrees Celsius for 2 hours to obtain a partitioned curing mold (9). Place the partitioned curing mold (9) on the flexible electrode array (4), with each flexible electrode unit corresponding to a space on the mold, ensuring that the mold and the flexible electrode array (4) fit together without gaps. Use a pipette to drop 20 μL of ion gel solution into the spaces in the mold. Heat at 60 degrees Celsius for 24 hours to cure, forming the 100 μm thick ion gel array (5), and obtain the top layer structure (1).

10. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials according to claim 8, characterized in that, The microstructure layer (2) is prepared by the following method: Pour the aliphatic aromatic random copolyester Ecoflex A and B adhesives into a container, mix them evenly, and then vacuum. Use a scraper to apply a 2mm thick layer of the mixed Ecoflex solution to the surface of sandpaper with a preset grit, and heat at 60°C for 2 hours to cure. Remove the sandpaper to obtain a silicone mold with a microstructure; apply a 3 mm thick ion gel solution to the silicone mold; heat at 60°C for 24 h to cure, forming a 300 μm thick microstructure ion gel thin layer (6); adsorb the microstructure ion gel thin layer (6) onto a conductive metal thin layer (7) to obtain the microstructure layer (2).

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