CN115371830A - Temperature-pressure self-decoupling flexible sensor based on microstructure ionic material - Google Patents

Abstract

The invention discloses a temperature-pressure self-decoupling flexible sensor based on a microstructure ionic material. The flexible electrode array is formed by sequentially laminating a top layer structure, a micro-structure layer and a substrate layer from top to bottom, wherein the upper surface of an ionic gel array in the top layer structure is contacted with the flexible electrode array; the lower surface of an ion gel array in the microstructure layer is in contact with the microstructure ion gel thin layer, the microstructure ion gel thin layer and the conductive metal thin layer are arranged in a stacked mode from top to bottom, the conductive metal thin layer is electrically connected with the signal output interface, the flexible electrode array, the ion gel array, the microstructure ion gel thin layer and the conductive metal thin layer form a capacitive pressure sensor, and the flexible electrode array, the ion gel array and the microstructure ion gel thin layer form a resistive temperature sensor. The multi-mode flexible sensor disclosed by the invention can simultaneously detect the temperature, the pressure and the approaching three sensing modes, the temperature and the approaching sensing modes are realized through partial structures in the pressure sensing modes, the integration level is high, and the space is compact.

Description

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

technical field

The invention relates to a flexible sensor in the technical field of sensors, in particular to a temperature-pressure self-decoupling multi-mode flexible sensor based on microstructured ionic materials.

Background technique

Human skin is soft, self-healing, and able to sense subtle environmental differences, such as breeze, which has stimulated a lot of research on artificial skin-like materials. When the machine completes the intelligent grasping work, it needs to accurately judge the grasping force to ensure Complete without damaging the target.

Ion gel is a solid mixture with ion conductivity, which is usually mixed with high molecular weight organic polymers and salt electrolyte materials that can be electrolyzed into ions, because the polymer molecular chains are connected or entangled with each other to form a spatial network. Like structure, the structural gap is filled with anions and cations as a dispersion medium, which is similar to the structure of traditional gel, so it is called "ionic gel". The polymers that make up ion gels are mostly colloidal block copolymers. The copolymers will form a cross-linked network structure, which provides high tensile strength for ion gels, and the network structure also provides support for the movement of ions. up the channel. The ionic liquid mixed in the polymer copolymer is a molten strong electrolyte, and this strong electrolyte will exist in the ion gel in the state of anion and cation in the molten state. Since the functional group of the copolymer has many coordination sites, the anions and cations are mostly connected with the functional group of the copolymer by coordination bonds in the state of no external electric field, and are dispersed in the whole ion gel. Under the action of an external electric field, the local movement of ions between the polymer chain and the ion coordination sites produces the migration of anions and cations, thereby generating an uneven charge distribution inside the ion gel, and the anions and cations are stacked at both ends of the interface, respectively. Form an electric double layer.

Temperature also changes the distribution of ions. As the temperature increases, the number of ions increases as more ions are released from the polymer network. Also, as the temperature increases, the ions gain more energy, so the ions move faster. When a potential difference is applied across the ionic material, more ions move to the electrode surface (i.e., are more polarized). Due to the existence of these two phenomena, the capacitance will increase with the increase of temperature. Therefore, when the electric double layer effect is used to test the pressure generated by an object with temperature, due to the contact, the temperature will change, and then the measured capacitance will be changed, resulting in an error in the measured pressure. Therefore, it is necessary to decouple the dual effects of temperature and pressure, eliminate the capacitance change caused by temperature changes, and accurately measure the pressure.

Contents of the invention

In order to solve the problem that when the electric double layer effect is used to test the pressure, due to the contact, the temperature will change, and then the measured capacitance will be changed, resulting in the error of the measured pressure, and the function of proximity sensing is realized. The present invention provides a Temperature-pressure self-decoupling flexible sensor based on microstructured ionic materials.

The technical scheme adopted in the present invention is:

The sensor is composed of a top structure, a microstructure layer and a base layer arranged sequentially from top to bottom. The top structure is provided with a lead-out tape, and the lead-out tape is bonded to the base layer, so that a pre-pressure is generated between the top structure and the microstructure layer;

The top layer structure includes a flexible electrode array and an ion gel array, and the upper surface of the ion gel array is in contact with the flexible electrode array, wherein each ion gel unit in the ion gel array completely covers the corresponding flexible electrode array 3. An electrode unit; the lower surface of the ion gel array is in contact with the upper surface of the microstructure layer;

The microstructure layer includes a microstructure ion gel thin layer, a conductive metal thin layer and a signal output interface, the lower surface of the ion gel array is in contact with the upper surface of the microstructure ion gel thin layer, and the microstructure ion gel thin layer The thin conductive metal layer is stacked from top to bottom, the thin conductive metal layer is electrically connected to the signal output interface, and the thin conductive metal layer is arranged on the base layer;

Flexible electrode array, ion gel array, microstructure ion gel thin layer and conductive metal thin layer constitute capacitive pressure sensor, wherein flexible electrode array and conductive metal thin layer are used as capacitive pressure sensor, wherein flexible electrode array and conductive metal thin layer Layers are used as two electrode plates of the capacitive pressure sensor, and the ion gel array and the thin ion gel thin layer of the microstructure are used as the dielectric layer of the capacitive pressure sensor;

The flexible electrode array and the ion gel array constitute a resistive temperature sensor; the flexible electrode array is used as an electrode of the resistive temperature sensor, and the ion gel array is used as a conductive medium of the resistive temperature sensor.

The flexible electrode array is composed of a plurality of flexible electrode units arranged in an N×M array, and each electrode unit has the same structure, including a central disc-shaped electrode and a semi-closed ring-shaped electrode. A central disk-shaped electrode is placed, and the central disk-shaped electrode and the ring-shaped electrode are arranged at intervals.

The base layer is a flexible PI film.

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

The side of the microstructure ion gel thin layer in contact with the ion gel array is provided with a micro-protrusion structure array, and the side of the microstructure ion gel thin layer in contact with the conductive metal thin layer is smooth.

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.

The thin conductive metal layer is made of copper foil.

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

First add dimethylacetamide DMAC to the beaker as a solvent, then add thermoplastic polyurethane elastomer TPU and [EMIM][TFSi] ionic liquid, the mass ratio of the three is 10:1:1; stir 12 on a magnetic stirrer Mix the three evenly; then place the ion gel solution after stirring in a vacuum defoamer for 20 minutes to remove air bubbles in the ion gel solution; heat the defoamed solution at 70°C 10 minutes, remove the moisture in the solution to obtain the ion gel solution;

The top layer structure is prepared by the following method:

Pour A and B glues of aliphatic aromatic random copolyester Ecoflex into the container, mix well and then vacuumize; pour the mixed Ecoflex solution into the mold, and heat at 60 degrees Celsius for 2 hours to obtain a partition To cure the mold, place the separate curing mold on the flexible electrode array, and each flexible electrode unit corresponds to the space on the mold to ensure that there is no gap between the mold and the flexible electrode array; use a pipette gun to use 20ul ion gel The solution was dropped into the space in the mold; heated at a constant temperature of 60° C. for 24 hours to solidify to form a 100 um thick ion gel array and obtain the top layer structure.

The microstructure layer is prepared by the following method:

Pour A and B glues of aliphatic aromatic random copolyester Ecoflex into the container, mix well and then vacuumize; use a scraper coater to scrape the mixed Ecoflex solution with a thickness of 2mm on the surface of the sandpaper with a preset mesh number, Heating at 60°C for 2 hours to cure; peel off the sandpaper to obtain a silica gel mold with a microstructure; scrape and coat a 3mm thick ion gel solution on the silica gel mold; heat and cure at a constant temperature of 60°C for 24h to form the microstructure with a thickness of 300um An ion gel thin layer; the microstructure ion gel thin layer is adsorbed on the conductive metal thin layer to obtain the microstructure layer.

Its beneficial effect of the present invention is:

When the present invention measures the pressure generated by an object with temperature, the temperature can be measured through the resistance measured by the top layer structure, the joint influence of temperature and pressure can be measured through the capacitance change, and the pressure on the sensor can be deduced to realize the temperature and pressure Self-decoupling, accurate measurement of pressure and temperature, has a great application prospect in artificial skin, robot intelligent grasping, etc.

The invention has the function of proximity sensing, can use the change of capacitance value to measure the proximity of the object, and can locate the relative position of the mechanical claw and the target when realizing the intelligent grasping work of the robot.

The invention imitates the suppleness and multi-modal sensing function of biological skin, and can independently measure various variables in the process of human-computer interaction. By multiplexing the same layer of electrodes to multiple sensing functions, the number of layers of the sensor device is simplified, and the thickness of each layer is optimized to ensure that the overall thickness is 500um, which realizes light and thin features and minimizes the robot skin. Restrictions on robot activity.

The invention utilizes the microstructure ion gel to make the pressure sensing function of the sensor have higher sensitivity and linearity.

The processing technology of the invention is simple, all steps can be precisely quantified, the molds can be reused, and the repeatability of equipment manufacturing is guaranteed to be good.

The present invention has an integrated signal output port, which can be quickly integrated on the surface of the robot body, end effectors, intelligent prosthetic hands and other equipment during application.

Description of drawings

Fig. 1 is the schematic exploded view of the structure of the ion gel sensor of the present invention;

Fig. 2 is the structural representation of ion gel sensor of the present invention

Fig. 3 is a top-level structural circuit diagram;

Fig. 4 is a schematic circuit diagram of the present invention;

Fig. 5 is the preparation process of described top layer structure;

Fig. 6 is the preparation process of described microstructure layer;

Fig. 7 is to separate curing mould;

Fig. 8 is the pressure cycle applied on the ion gel;

Fig. 9 is the resistance change corresponding to the ion gel;

Figure 10 is a temperature-resistance calibration curve;

Figure 11 is a temperature-capacitance calibration curve;

Figure 12 is a pressure-capacitance calibration curve.

In the figure: top layer structure 1, microstructure layer 2, base layer 3, flexible electrode array 4, ion gel array 5, microstructure ion gel thin layer 6, conductive metal thin layer 7, signal output interface 8, center wafer Type electrode 41, ring type electrode 42, separate curing mold 9.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 and Fig. 2, the present invention is composed of a top layer structure 1, a microstructure layer 2 and a base layer 3 arranged sequentially from top to bottom. Adhesive on the base layer 3, so that there is a pre-pressure between the top layer structure 1 and the microstructure layer 2, which has higher sensitivity; the top layer structure is used to detect the temperature of the contact point, and it is necessary to avoid pressure on the resistance of the material as much as possible influences. Due to the need to use the electric double layer effect to test the capacitance, the contact resistance between the top structure and the microstructure layer is unavoidable. By controlling the ion concentration of the ion gel, the sheet resistance can be increased, thereby reducing the contact resistance effect. The base layer 3 is cut and shaped by a flexible PI film to ensure the flexibility of the sensor.

The top 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 and in close contact with the flexible electrode array 3, wherein each ion gel unit in the ion gel array 5 is completely Covering the corresponding flexible electrode unit in the flexible electrode array 3; the lower surface of the ion gel array 5 is in close 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 close contact with the upper surface of the microstructure ion gel thin layer 6, and the microstructure The 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, and the conductive metal thin layer 7 is arranged on the base layer 3;

The microstructure layer is combined with the top layer structure, and the two layers of ion gel are in contact with each other to produce an electric double layer effect. When two polymers are brought into contact with each other and a potential difference is applied across the two layers, the ions are redistributed according to their polarity. The electric field is formed by the interaction of positive and negative ions. As the contact area increases, the capacitance also increases due to the increased electric field. The thin layer of the microstructure ion gel is smooth on one side, and the microstructure is 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; The consistency and uniformity of the microstructure at the macroscopic level, when the sensor is pressed, as the pressure increases, the contact area of the two layers of ion gel will increase uniformly, the sensor has Higher sensitivity and linearity; the thickness of the microstructure ion gel thin layer needs to ensure complete coverage of the microstructure on the sandpaper, but does not affect the capacitance and resistance characteristics of the sensor, and the minimum can reach 300um.

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 are used as a capacitive pressure sensor, wherein, The central disc-shaped electrode 41 in each flexible electrode unit in the flexible electrode array, the ion gel unit attached to it, the thin layer of microstructured ion gel and the thin layer of conductive metal can be regarded as a capacitive pressure sensing unit , the capacitive signal of the capacitive pressure sensing unit is jointly drawn out by the central disc-shaped electrode 41 and the conductive metal thin layer. The flexible electrode array 4 and the conductive metal thin layer 7 are respectively used as two parallel electrode plates of the capacitive pressure sensor, and the ion gel array 5 and the microstructure ion gel thin layer 6 are used as the dielectric layer of the capacitive pressure sensor, and the conductive The thin metal layer 7 can sense the approach of an external conductive object by measuring the change in capacitance to ground generated when the conductor approaches, and the measurement of the capacitance of the capacitive pressure sensor reflects the magnitude and distribution of pressure imposed by the external environment;

The flexible electrode array 4 and the ion gel array 5 constitute a resistive temperature sensor, which detects temperature changes through resistance changes. Each flexible electrode unit and the ion gel unit attached to it can be regarded as a resistive temperature sensor, and the resistance signal is jointly drawn out by the central disc electrode 41 and the semi-closed ring electrode 42; the flexible electrode array 3 acts as a resistor The electrodes of the resistive temperature sensor, and the ion gel array 5 is used as the conductive medium of the resistive temperature sensor.

In the temperature sensing module, the temperature of the detection point can be calculated by measuring the resistance of the ion gel at the corresponding detection point through the central disc-shaped electrode and the ring-shaped electrode; in the pressure sensing module, the central disc-shaped electrode serves as One pole of capacitance measurement; for plate capacitance, the electric field strength between two plates determines the size of the capacitance, and the electrode area determines the electric field strength again, and the sensitivity of the sensor can be improved by adopting a larger central disk electrode. The ion gel needs to be configured to scale. Adding more ionic liquids to 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. A trade-off between electrical and mechanical properties is therefore required.

In summary, the multimodal flexible sensor disclosed in the present invention can simultaneously detect three sensing modes of temperature, pressure and proximity. The temperature and proximity sensing modes are realized by partial structures in the pressure sensing mode, with high integration and compact space.

The multi-modal flexible sensor disclosed in the present invention utilizes the insensitivity of the resistance value of the ionic material itself to external forces, decouples the dual influence of temperature and pressure on the capacitance value in the capacitive pressure sensing mode, and eliminates the capacitance change caused by the temperature change , to accurately measure the pressure applied to the sensor. When measuring the pressure generated by an object with temperature, the present invention can calculate the multi-point temperature distribution through the resistance measured by the ion gel array in the top structure, and measure the temperature and capacitance changes by calibrating the capacitance change in the pressure sensing mode The joint influence relationship curve with pressure, according to the temperature value calculated by the current resistance, deduces the pressure on the sensor, realizes the self-decoupling of temperature and pressure, and accurately measures pressure and temperature. The decoupling process only involves capacitance The ionic material of the pressure sensor itself does not require other materials, and no other temperature sensors need to be installed outside the sensor, which realizes self-decoupling in the sense of ionic materials and self-decoupling in the sense of sensor devices. Through the design of the signal acquisition circuit, When using the proximity sensing module, the central disc-shaped electrodes on the flexible electrode array can be connected in series to form a large capacitance to ground; the proximity of the object can be measured by using the change in capacitance value caused by the approach of the object .

As shown in Figure 3, the flexible electrode array 4 is composed of a plurality of flexible electrode units coplanarly arranged in an N×M array, and each electrode unit has the same structure, including a central disc-shaped electrode 41 and a semi-closed ring A circular electrode 42, a central disk electrode 41 is placed inside the ring electrode 42, and the center disk electrode 41 and the ring electrode 42 are arranged at intervals. The central disc-shaped electrode 41 of each flexible electrode unit uses a signal output interface alone to output signals independently, such as the signal output interfaces 1_1-1_9 of Figure 3 and Figure 4; the ring-shaped electrodes 42 are connected in series and share a signal output interface , as shown in the signal output interface 1_0 of 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 result. The capacitance between each group of electrodes can be measured through the signal output port 8 and the signal output ports 1_1-1_9, and the result under the joint influence of temperature and pressure can be obtained by comparing with the calibration result. Then through the calculation of self-decoupling, 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 temperature of the detection point can be calculated by measuring the resistance of the ion gel at the corresponding detection point through each central disc-shaped electrode 41 and the ring-shaped electrode 42; in the pressure sensing module, the central disc-shaped electrode 42 Electrode 41 is used as a pole for capacitance measurement; for plate capacitance, the electric field strength between two plates determines the size of the capacitance, and the area of the electrodes determines the electric field strength. The use of the central disc electrode 41 can improve the sensitivity of the sensor.

The base layer 3 is a flexible PI film, and the thickness of the flexible PI film is 50 μm, which helps to reduce the overall thickness of the sensor, and is conducive to the application in intelligent grasping of robots, artificial skin, etc.

The ion gel array 5 is composed of a plurality of ion gel units coplanarly arranged into an N×M array; the thickness of the ion gel array 5 does not affect the sensor capacitance and resistance performance, and can be reduced as much as possible under the premise of ensuring complete coverage of the electrodes. The thickness of the small gel reaches about 100um; there is no contact between the ion gel units of the ion gel array 5, mutual insulation is realized, and data is provided independently during the working process; the resistance of the ion gel array 5 is not sensitive to pressure, In the temperature sensing module, the temperature of the ion gel unit can be calculated by measuring the resistance value of the ion gel; in the pressure sensing module, the ion gel array 5 is used as one layer of the electric double layer structure; The ion gel used in gel array 5 requires organic solvents, including dimethylacetamide DMAC; requires elastic polymers, including thermoplastic polyurethane elastomer TPU; requires ionic liquid IL, including [EMIM][TFSi]; ion gel The mass ratio of each component material in the array 5 is dimethylacetamide DMAC:thermoplastic polyurethane elastomer TPU:ionic liquid IL=8:1:1 to 12:1:1. Ensure that the prepared solution has a low viscosity to meet the requirements of subsequent operations.

The side of the microstructure ion gel thin layer 6 in contact with the ion gel array 5 is provided with a micro-protrusion structure array. In the specific implementation, the microstructure is prepared by using sandpaper. After the mesh number of the sandpaper is determined, it can produce The microstructure of the sensor has good repeatability; due to the consistency and uniformity of the microstructure prepared by sandpaper, during the process of pressing the sensor, as the pressure increases, the contact between the two layers of ion gel The area will increase uniformly accordingly, thereby increasing the sensitivity and linearity of the capacitive pressure sensor. The side of the microstructure ion gel thin layer 6 in contact with the conductive metal thin layer 7 is smooth; the thickness of the microstructure ion gel thin layer 6 needs to ensure that the microstructure on the sandpaper is completely covered, but does not affect the capacitance and resistance characteristics of the sensor. It can reach 300um; the microstructured ion gel thin layer 6 is used as a layer of the electric double layer in the pressure sensing module; the capacitance of the electric double layer depends on the contact area. When the sensor is pressed, the microstructured ion gel thin layer The layer 6 is deformed, and the contact area with the ion gel array 5 increases, resulting in an increase in sensor capacitance;

Formulation of ion gels used in microstructured ion gel thin layers6 requires organic solvents, including dimethylacetamide DMAC; elastic polymers, including thermoplastic polyurethane elastomer TPU; and ionic liquids, including [EMIM][TFSi] ; The mass ratio of each component material is dimethylacetamide DMAC: thermoplastic polyurethane elastomer TPU: ionic liquid IL = 10:1:1.

The thin conductive metal layer 7 is made of copper foil, and its thickness is usually tens of microns. As a pole in a parallel plate capacitor, it helps to reduce the overall thickness of the sensor; the adhesive surface of the thin conductive metal layer 7 adheres to the substrate 3 , to ensure stable bonding, and the relative position between the layers is fixed during the pressure process of the sensor; the metal surface of the conductive metal thin layer 7 is bonded to the microstructure ion gel thin layer 6 through the adhesion of the ion gel itself; the conductive metal The thin layer 7 has high fatigue resistance and flexibility, and can maintain stable performance during long-term use.

The preparation method of the ion gel solution of the ion gel array 5 is as follows:

First, add dimethylacetamide DMAC as a solvent into a clean and dry beaker, then add thermoplastic polyurethane elastomer TPU and [EMIM][TFSi] ionic liquid, the mass ratio of the three is 10:1:1; Stir for 12 hours to make the three mix evenly; then place the ion gel solution after stirring in a vacuum defoamer for defoaming for 20 minutes to remove the bubbles in the ion gel solution; put the defoamed solution in Heat at 70°C for 10 minutes to remove the moisture in the solution; pour the solution into a dry and clean glass container, seal it and store it to obtain an ionic gel solution; adding more ionic liquid to the sample can increase the free The number of ions, 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 properties and mechanical properties is required according to the requirements of the application scenario; the ion gel used in the thin layer of the microstructure ion gel Organic solvents are required during configuration, including dimethylacetamide DMAC; elastic polymers are required, including thermoplastic polyurethane elastomer TPU; ionic liquid IL is required, including [EMIM][TFSi]; the mass ratio during configuration is DMAC:TPU:IL= 10:1:1. Ensure that the configured solution has a certain viscosity to meet the requirements of subsequent operations.

As shown in Figure 5, the top structure 1 is prepared by the following method:

Pour A and B glues of aliphatic aromatic random copolyester Ecoflex into the container, mix well and then vacuumize; pour the mixed Ecoflex solution into the mold, and heat at 60 degrees Celsius for 2 hours to obtain a partition Curing mold 9, as shown in Figure 6, carefully place the separate curing mold 9 on the flexible electrode array 4, and each flexible electrode unit corresponds to the space on the mold to ensure that there is no gap between the mold and the flexible electrode array 4; Spray 20ul ion gel solution into the space in the mold with a gun; heat at 60°C for 24 hours to cure, and form a 100um thick ion gel array 5; carefully remove the partition curing mold to obtain the top layer structure 1; partition the curing mold 9 It can be used repeatedly, and all steps can be accurately quantified to ensure good repeatability of equipment manufacturing.

As shown in Figure 6, the microstructure layer 2 is prepared by the following method:

Pour A and B glues of aliphatic aromatic random copolyester Ecoflex into the container, mix well and then vacuumize; use a scraper coater to scrape the mixed Ecoflex solution with a thickness of 2mm on the surface of the sandpaper with a preset mesh number, Heating at 60°C for 2 hours to cure; peel off the sandpaper to obtain a microstructured silica gel mold; scrape and coat a 3mm thick ion gel solution on the silica gel mold; heat and cure at a constant temperature of 60°C for 24 hours to form a 300um thick microstructure ion gel Adhesive thin layer 6; the microstructured ion gel thin layer 6 is adsorbed on the conductive metal thin layer 7 (the side of the copper foil without glue) by utilizing the inherent adsorption capacity of the smooth surface of the ion gel to obtain a microstructured layer 2; The silicone mold of the structure can be reused, and all steps can be accurately quantified to ensure the repeatability of the performance of the microstructure layer prepared each time.

The signal output interface 8 is bonded on the base layer 3 with a conductive adhesive; the signal output interface 8 is wrapped with an insulating tape to prevent the corrosion of the electrode and the change in conductivity caused by changes in the external environment; through the signal output interface 8, the conductive metal The thin layer 7 is output as the electrical signal measured by the common electrode of each detection point in the pressure sensing module.

The sensor can take advantage of the insensitivity of the resistance value of the ionic material itself to external forces to decouple the dual effects of temperature and pressure in the decoupling pressure sensing mode, eliminate the capacitance change caused by temperature changes, and accurately measure the pressure applied to the sensor ; When the present invention measures the pressure that the object with temperature produces, can calculate multi-point temperature distribution by the resistance measured by the ion gel array 5 in the top structure 1, by calibrating capacitance and temperature, capacitance and The pressure relationship curve, based on the temperature value calculated by the current resistance, and then using the capacitance and temperature relationship curve, deduces the capacitance change caused by temperature and excludes the change, obtains the pressure on the sensor, and realizes the self-decoupling of temperature and pressure , to accurately measure the pressure and temperature; the decoupling process only involves the ionic material of the capacitive pressure sensor itself, no other materials are needed, and no other temperature sensors need to be set outside the sensor, realizing self-decoupling in the sense of ionic materials And self-decoupling in the sense of sensing devices.

Through the design of the signal acquisition circuit, when using the proximity sensing module, the central disc-shaped electrode 41 on the flexible electrode array 4 can be connected in series to form a larger capacitance to ground, and the capacitance value change caused by the approach of the object can be utilized. The approaching situation of the object can be measured; the conductive metal thin layer 7 can also be regarded as a larger electrode, and the variation of the ground capacitance of the electrode caused by the object approaching can be used to measure the approaching situation of the object; The central disc-shaped electrodes 41 are connected in series to form a larger electrode, which forms a mutual capacitance with the thin conductive metal layer 7, and the proximity of the object can be measured by using the change in the mutual capacitance value of the electrode pair caused by the approach of the object.

As shown in Figure 8, a 0-1N cycle pressure is applied to the ion gel, and the corresponding resistance change of the ion gel is shown in Figure 9; under the pressure cycle, the resistance change rate of the ion gel is less than 1%, indicating that Ion gel is a material that is not sensitive to pressure. During the process of pressure, the temperature of the contact point can still be accurately measured through resistance, which ensures the reliability and accuracy of the temperature sensing module.

As shown in Figure 10, keep the pressure at 0.01N, change the temperature at 10-60°C, and change the resistance correspondingly in the range of 2.3-0.22MΩ, with a change rate of 1000%. The measured resistance can be combined with the calibration results. Estimates the temperature at the detection point of the sensor.

As shown in Figure 11, the guaranteed pressure is 2N, and the pressure sensing module of the sensor can reach the maximum range at this time. When the temperature is changed at 10-60°C, the corresponding capacitance changes in the range of 580-3650pF, and the change rate is 5300%. Since the capacitance value of the electric double layer is determined by the contact area and ion concentration, and the temperature change only changes the ion concentration and does not change the contact area, the temperature capacitance calibration curve can be used to calculate the change ratio of the sensor capacitance value caused by the temperature change. Therefore, the measured temperature value can be combined to calculate the equivalent capacitance value at 20°C.

As shown in Figure 12, under the room temperature condition of 20°C, as the pressure increases from 0 to 0.5N, the capacitance of the sensor changes from 40pF to 1000pF correspondingly, and the change rate is 2500%. The equivalent capacitance value calculated in the previous stage can be used to calculate the pressure on the sensor and complete the accurate measurement of temperature and pressure.

Claims (10)

1. A temperature-pressure self-decoupling flexible sensor based on a microstructure ionic material is characterized by being formed by sequentially stacking a top layer structure (1), a microstructure layer (2) and a substrate layer (3) from top to bottom, wherein the top layer structure (1) is provided with a leading-out belt which is adhered to the substrate layer (3) so that pre-pressure is generated between the top layer structure (1) and the microstructure layer (2);

the top layer structure (1) comprises a flexible electrode array (4) and an ionic gel array (5), the upper surface of the ionic gel array (5) is in contact with the flexible electrode array (3), and each ionic gel unit in the ionic gel array (5) completely covers the corresponding flexible electrode unit in the flexible electrode array (3); the lower surface of the ionic gel array (5) is in contact with the upper surface of the microstructure layer (2);

the microstructure layer (2) comprises 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 arranged in a stacking mode from top to bottom, 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 substrate layer (3);

the flexible electrode array (4), the ion gel array (5), the microstructure ion gel thin layer (6) and the conductive metal thin layer (7) form a capacitive pressure sensor, wherein the flexible electrode array (4) and the conductive metal thin layer (7) are used as the capacitive pressure sensor, the flexible electrode array (4) and the conductive metal thin layer (7) are respectively used as two electrode plates of the capacitive pressure sensor, and the ion gel array (5) and the microstructure ion gel thin layer (6) are used as dielectric layers of the capacitive pressure sensor;

the flexible electrode array (4) and the ionic gel array (5) form a resistance type temperature sensor; the flexible electrode array (3) is used as an electrode of the resistance temperature sensor, and the ionic gel array (5) is used as a conductive medium of the resistance temperature sensor.

2. The flexible temperature-pressure self-decoupling sensor based on microstructured ionic materials as claimed in claim 1, wherein the flexible electrode array (4) is composed of a plurality of flexible electrode units arranged in an N × M array, each electrode unit has the same structure and comprises a central circular-disc-type electrode (41) and a semi-closed circular-ring-type electrode (42), the central circular-disc-type electrode (41) is disposed inside the circular-ring-type electrode (42), and the central circular-disc-type electrode (41) and the circular-ring-type electrode (42) are spaced apart from each other.

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

4. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic material according to claim 1, characterized in that the ionic gel array (5) is composed of a plurality of ionic gel units arranged in an N x M array; the mass ratio of each component material in the ionic gel array (5) is Dimethylacetamide (DMAC): thermoplastic polyurethane elastomer TPU: ionic liquid IL =8:1:1 to 12:1: 1.

5. The temperature-pressure self-decoupling flexible sensor based on the microstructure ionic material as claimed in claim 1, wherein the microstructure ionic gel thin layer (6) is provided with a micro-protrusion structure array on the side in contact with the ionic gel array (5), and the microstructure ionic gel thin layer (6) is smooth on the side in contact with the conductive metal thin layer (7).

6. The temperature-pressure self-decoupling flexible sensor based on the microstructure ionic material as claimed in claim 1, wherein the mass ratio of each component material in the microstructure ionic gel thin layer (6) is Dimethylacetamide (DMAC): thermoplastic polyurethane elastomer TPU: ionic 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 thin conductive metal layer (7) is made of copper foil.

8. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic material according to claim 1, characterized in that the ionic gel solution of the ionic gel array (5) is prepared as follows:

firstly, adding Dimethylacetamide (DMAC) into a beaker as a solvent, and then adding thermoplastic polyurethane elastomer (TPU) and [ EMIM ] [ TFSi ] ionic liquid, wherein the mass ratio of the DMAC to the TPU to the [ EMIM ] [ TFSi ] ionic liquid is 10:1:1; stirring the mixture on a magnetic stirrer for 12 hours to uniformly mix the three components; then placing the stirred ionic gel solution in a vacuum defoaming machine for defoaming for 20 minutes to remove bubbles in the ionic gel solution; the defoamed solution was heated at 70 ℃ for 10 minutes, and water in the solution was removed to obtain an ionic gel solution.

9. A temperature-pressure self-decoupling flexible sensor based on microstructured ionic material according to claim 8, characterized in that the top layer structure (1) is prepared by the following method:

pouring the A and B glue of aliphatic aromatic random copolyester Ecoflex into a container, uniformly mixing, and vacuumizing; pouring the mixed Ecoflex solution into a mold, heating at 60 ℃ for 2 hours to prepare a separation curing mold (9), placing the separation curing mold (9) on the flexible electrode array (4), wherein each flexible electrode unit corresponds to a blank on the mold, and ensuring that no gap exists between the mold and the flexible electrode array (4); dripping 20ul of ionic gel solution into the blank in the mould by using a liquid-transfering gun; heating at the constant temperature of 60 ℃ for 24h for curing to form the ionic gel array (5) with the thickness of 100um, and obtaining the top layer structure (1).

10. The temperature-pressure self-decoupling flexible sensor based on microstructured ionic material of claim 8, wherein the microstructured layer (2) is prepared by:

pouring the A and B glue of aliphatic aromatic random copolyester Ecoflex into a container, uniformly mixing, and vacuumizing; coating the mixed Ecoflex solution with the thickness of 2mm on the surface of sand paper with a preset mesh number by using a coating machine, and heating for 2 hours at 60 ℃ for curing; removing the sand paper to obtain a silica gel mold with a microstructure; coating ionic gel solution with the thickness of 3mm on a silica gel mold in a scraping way; heating at the constant temperature of 60 ℃ for 24h for curing to form the microstructure ionic gel thin layer (6) with the thickness of 300um; and adsorbing the microstructure ionic gel thin layer (6) on a conductive metal thin layer (7) to obtain the microstructure layer (2).

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