High-range high-sensitivity three-electrode ionizing pressure sensor and preparation method thereof

Abstract

The invention relates to the field of flexible electronic sensors, in particular to a high-range and high-sensitivity three-electrode ionization pressure sensor and a preparation method thereof. The three-electrode ionization pressure sensor comprises a flexible packaging shell, three layers of flexible electrodes packaged in the flexible packaging shell, two sensitive layers with microstructures and arranged between the flexible electrodes, and spacing layers arranged between the flexible electrodes and the sensitive layers with the microstructures, the flexible electrodes and the sensitive layers with the microstructures are arranged in a crossed and stacked manner, and the two sensitive layers with the microstructures are provided with sensitive layer microstructures with different scales. The linear sensing range is enhanced by arranging the two sensitive layers with the microstructures of different scales, and the effect of widening the linear range of the sensor can be achieved; the sensor has excellent performance and has extremely high application potential in motor monitoring and motor intelligent interaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible electronic sensors, in particular to a high-range and high-sensitivity three-electrode electrostatic voltage pressure sensor and a preparation method thereof. BACKGROUND

[0002] In recent years, an innovative sensing technology—electrostatic sensor technology, has rapidly risen due to its unique working principle and significant performance advantages. This technology is based on the super-capacitance characteristics of the double electric layer at the interface of the electrode sensitive layer, opening up a new way of pressure and tactile detection. Compared with traditional sensing technology, electrostatic sensors stand out with their thin profile, excellent flexibility, ultra-high sensitivity and fine resolution, especially suitable for capturing subtle static and dynamic changes. Electrostatic sensors adjust the capacitance value by detecting the formation and contact area change of the double electric layer under pressure, achieving accurate monitoring of pressure changes. This technology not only has much higher sensitivity and resolution than traditional sensors, but also can endow various materials with intelligent tactile function, making it show broad application potential in motor technology and robotics. With the continuous progress of intelligent technology, especially in the frontier fields of intelligent robots, intelligent interaction of motors and health monitoring of motors, electrostatic sensor technology is attracting attention due to its ability to achieve high integration and functional diversity, indicating a new era of intelligent sensing technology.

[0003] However, traditional capacitive (double electrode) sensors have some limitations, mainly due to the current flexible pressure sensors, which pursue high sensitivity by using a sensitive layer with microstructure, resulting in small range and small linear range. In order to achieve higher sensitivity, such traditional electrostatic pressure sensors continuously reduce the initial capacitance value, replace materials with better performance, and increase the contact area between the sensitive layer microstructure under stress and the electrode, thereby ignoring the importance of high range and high linear range of the sensor, limiting its application in high linear measurement environments. SUMMARY

[0004] The present application aims to provide a three-electrode electrostatic voltage pressure sensor with high range, high sensitivity and high linear range, and a preparation method thereof, to solve the problems of small range, small linear range and weak anti-interference ability of existing traditional double-electrode capacitive sensors.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: The application discloses a high-range and high-sensitivity three-electrode ion electric voltage pressure sensor, which comprises a flexible packaging shell, three layers of flexible electrodes packaged in the flexible packaging shell, two layers of sensitive layers with microstructures arranged between the flexible electrodes, and a spacing layer arranged between the flexible electrodes and the sensitive layers with microstructures, the flexible electrodes and the sensitive layers with microstructures are arranged in cross-stacking mode, and the two layers of sensitive layers with microstructures are provided with sensitive layer microstructures with different sizes; the flexible electrode comprises a flexible substrate, a flexible conductive layer and a lead-out wire, the lead-out wire is arranged on the flexible substrate and is subjected to insulation packaging treatment; the sensitive layer with microstructure comprises a sensitive layer bottom plate and sensitive layer microstructures integrally formed on the sensitive layer bottom plate, the sensitive layer microstructures are arranged in a rectangular array form, and the shape of the sensitive layer microstructures comprises, but is not limited to, a dome structure, a pyramid, a cylinder and a sandpaper structure. In the high-range and high-sensitivity three-electrode ion electric voltage pressure sensor, the thickness of the flexible packaging shell is controlled to be less than 0.5 mm, and any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and silica gel is used to prepare the flexible packaging shell, so that the flexible packaging shell has certain flexibility and stretchability, sufficient mechanical strength and durability, and can meet the stretching and bending requirements in different working environments.

[0006] In the high-range and high-sensitivity three-electrode ion electric voltage pressure sensor, the sensitive layer with microstructure is prepared by means of reverse molding and 3D additive printing, one side of the sensitive layer with microstructure is smooth, and the other side is distributed with dense sensitive layer microstructures; the size of the sensitive layer microstructures accounts for about 0.5-0.25 of the overall size of the sensor, and the excessively thick integrated sensor affects arrangement, and the excessively thin sensor loses sensing effect.

[0007] In the high-range and high-sensitivity three-electrode ion electric voltage pressure sensor, the sensitive layer bottom plate has excellent flexibility, stretchability, chemical stability and non-conductivity and other characteristics, and any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and polyurethane (PU) is used to prepare the sensitive layer bottom plate; the sensitive layer microstructures are prepared from an ionic medium material and an adsorption material, wherein the ionic medium material is an imidazole ionic liquid or a pyridine ionic liquid; and the adsorption material is boron nitride (BN) or silicon dioxide (SiO2).

[0008] In the high-range and high-sensitivity three-electrode ion electric voltage pressure sensor, the spacing layer is arranged between the sensitive layer with microstructure and the flexible electrode, the spacing layer has good flexibility, the thickness of the spacing layer is between 0.1 mm and 0.2 mm, and any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and polyurethane (PU) is used to prepare the spacing layer.

[0009] In the high-range high-sensitivity three-electrode ion electric voltage pressure sensor, the flexible substrate has certain flexibility, sufficient strength, good chemical stability and is easy to process and shape, and is prepared from any one of polyimide (PI), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) and silica gel film and the like.

[0010] The application further provides a preparation method of the high-range high-sensitivity three-electrode ion electric voltage pressure sensor. S1, preparing a flexible electrode by sputtering a gold target material; S2, preparing a sensitive layer with a microstructure; The substrate medium material, the ion medium material and the silicon dioxide are mixed in proportion, the gas mixed in the liquid is removed by a vacuum machine, then the mixture is poured into a mold, vacuum drying is performed for 24 hours, demolding is performed, and the sensitive layer with the microstructure is obtained. S3, preparing a flexible packaging shell by using a 3D printing mold; S4, preparing a spacing layer by using a laser cutting or a reverse mold method; S5, preparing a three-electrode ion electric voltage pressure sensor; The flexible packaging shell, the flexible electrode, the spacing layer and the sensitive layer with the microstructure are stacked together in the stacking order of flexible electrode-spacing layer-sensitive layer with the microstructure-flexible electrode-sensitive layer with the microstructure-spacing layer-flexible electrode, wherein the flexible packaging shell and the flexible electrode and the flexible electrode and the spacing layer are adhered by 3M double-sided adhesive, and other layers are combined after being stacked freely.

[0011] Compared with the prior art, the application has the following beneficial effects: 1) The three-electrode ion electric voltage pressure sensor has the characteristics of high range, high sensitivity, high linear range and strong anti-interference ability.

[0012] 2) The application sets the double-layer sensitive layer with different scale microstructures to enhance the linear sensing range, wherein the small-scale microstructure is mainly used as the main body of linear sensing in the low-pressure stage, and the large-scale microstructure is mainly used as the main body of linear sensing in the high-pressure stage, and the three-electrode double capacitors formed by the two can realize the effect of widening the linear range of the sensor.

[0013] 3) The present application can greatly improve the ion adsorption effect and the sensitivity of the sensor by adding ion adsorption materials to the sensitive layer material, which can form an ion aggregation network inside the material. At the same time, the adsorption material can also modify the mechanical properties of the sensitive layer material, which has a beneficial effect on the Young's modulus and can improve the sensor range.

[0014] 4) The sensor prepared by the present application has excellent performance, and has high application potential in motor monitoring and intelligent motor interaction. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic diagram of a high-range and high-sensitivity three-electrode ion electric pressure sensor according to an embodiment of the present application.

[0016] Figure 2 It is a schematic diagram of the design principle of a high-range and high-sensitivity three-electrode ion electric pressure sensor according to an embodiment of the present application.

[0017] Figure 3 It is a schematic diagram of the working conditions of a high-range and high-sensitivity three-electrode ion electric pressure sensor and a two-electrode sensor according to an embodiment of the present application.

[0018] Figure 4 It is a pressure output comparison curve diagram of a high-range and high-sensitivity three-electrode ion electric pressure sensor and a two-electrode sensor according to an embodiment of the present application.

[0019] Figure 5 It is an output curve diagram of a high-range and high-sensitivity three-electrode ion electric pressure sensor at different pressure stages according to an embodiment of the present application.

[0020] In the figure: 1 - flexible packaging shell, 2 - flexible electrode, 21 - flexible substrate, 22 - flexible conductive layer, 3 - spacer layer, 4 - sensitive layer with microstructure, 41 - sensitive layer bottom plate, 42 - sensitive layer microstructure. DETAILED DESCRIPTION

[0021] The present application will be described in detail below with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0022] In order to solve the problems of small range, small linear range and weak anti-interference ability of the existing traditional two-electrode capacitive sensor, the present application provides a high-range, high-sensitivity, high-linear-range three-electrode ion electric pressure sensor, as shown in Figure 1As shown, the three-electrode ion electric voltage pressure sensor comprises a flexible packaging shell 1, three layers of flexible electrodes 2 packaged in the flexible packaging shell 1, two layers of micro-structured sensitive layers 4 arranged between the flexible electrodes 2, and a spacing layer 3 arranged between the flexible electrodes 2 and the micro-structured sensitive layers 4, the flexible electrodes 2 and the micro-structured sensitive layers 4 are arranged in cross-stacked manner, and the two layers of micro-structured sensitive layers 4 are provided with sensitive layer micro-structures of different sizes; each flexible electrode 2 comprises a flexible substrate 21, a flexible conductive layer 22, and a lead-out wire arranged on the flexible substrate 21 and subjected to insulation packaging treatment. The micro-structured sensitive layer 4 comprises a sensitive layer base plate 41 and a sensitive layer micro-structure 42 integrally formed on the sensitive layer base plate 41, the sensitive layer micro-structure 42 is arranged in a rectangular array form, and the shape of the sensitive layer micro-structure includes but is not limited to a dome structure, and common pyramids, cylinders, sandpaper structures and the like can also be used.

[0023] The flexible packaging shell of the present application can be prepared by any one of the processes such as reverse molding, 3D additive printing and laser etching, and needs to have certain flexibility, stretchability, sufficient mechanical strength and durability to adapt to the stretching and bending requirements in different working environments, and should be as light and thin as possible to maintain the flexibility of the sensor. Therefore, the flexible packaging shell of the present application can adopt any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and silica gel materials.

[0024] In order to reduce the excessive influence of the flexible packaging shell on the sensor sensing, the thickness of the flexible packaging shell is as light and thin as possible and is controlled within 0.5 mm.

[0025] The micro-structured sensitive layer 4 of the present application is prepared by reverse molding and 3D additive printing, one side of which is smooth, and the other side of which is distributed with dense sensitive layer micro-structures 42, the size of the sensitive layer micro-structure 42 accounts for about 0.5-0.25 of the overall size of the sensor, and the over-thick integrated sensor will affect the arrangement, and the over-thin sensor will lose the sensing effect.

[0026] In the micro-structured sensitive layer 4 of the present application: The sensitive layer base plate 41 can be prepared by using any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and polyurethane (PU) materials, and has excellent flexibility, stretchability, chemical stability and non-conductivity and other characteristics.

[0027] The sensitive layer micro-structure 42 is prepared from an ionic medium material and an adsorbing material, wherein the ionic medium material can be any one of imidazole ionic liquid or pyridine ionic liquid and other materials; and the adsorbing material can be any one of boron nitride (BN) or silicon dioxide (SiO2) and other materials.

[0028] The micro-structured sensitive layer 4 of the present application is spaced apart from the flexible electrode 2 by a spacer layer 3 at both ends, which can be prepared by any one of processes such as reverse molding, laser cutting of film and 3D additive printing, has a thickness of 0.1-0.2 mm and is prepared from any one of materials such as polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and polyurethane (PU), and has good flexibility. When stressed, the spacer layer 3 is extruded and deformed, the micro-structured sensitive layer 4 and the flexible electrode 2 start to contact, and then, as the pressure gradually increases, the contact area between the flexible electrode 2 and the ion fiber layer of the sensitive layer 4 gradually increases.

[0029] The flexible electrode 2 of the present application can be prepared by any one of processes such as sputtering, screen printing and laser cutting of copper foil, gold foil, etc., wherein: The flexible substrate 21 is prepared from any one of materials such as polyimide (PI), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) and silicone film, has certain flexibility, sufficient strength, good chemical stability and is easy to process and shape.

[0030] The flexible conductive layer 22 is prepared from any one of materials such as stretchable conductive silver paste, liquid metal, carbon nanotubes (CNTs), graphene (GR), carbon black (CB), copper foil (Cu) and gold foil (Au), has excellent conductivity, stability, sufficient strength and is easy to process.

[0031] It is worth noting that the flexible electrode 2 in the present application is distinguished between single-sided electrode and double-sided electrode, the difference lies in whether the flexible conductive material is coated on one side or both sides of the flexible substrate. The electrode formed by coating the flexible conductive material on one side is a single-sided electrode, and the electrode formed by coating the flexible conductive material on both sides is a double-sided electrode. The conductive materials on the front and back of the double-sided electrode are not isolated, but connected.

[0032] The three-electrode ion-electric voltage pressure sensor proposed in the present application is mainly based on the ion-electric effect theory, which is mainly established on the electric double layer (EDL) between the ion of the micro-structured sensitive layer 4 and the electron contact of the flexible electrode 2 and the change of the contact area therebetween. Figure 2 The simplified model of the three-electrode ion-electric voltage pressure sensor of the present application is shown, the two sensitive capacitors formed by the three electrodes are in parallel, so the total capacitance of the sensor is the sum of the two, i.e. Ctotal = C1 + C2.

[0033] Figure 3The three-electrode ion electric pressure sensor of the present application and the traditional two-electrode sensor are shown in the comparison of the sensor states under different pressures. It can be seen that when not under stress, the micro-structured sensitive layer 4 and the flexible electrode 2 are in a non-contact state, and the two are separated by the spacer layer 3; when under stress, the micro-structured sensitive layer 4 and the flexible electrode 2 start to contact, and then as the pressure gradually increases, the contact area between the flexible electrode 2 and the micro-structured sensitive layer 4 gradually increases, so that the sensor capacitance increases, and finally the pressure value is inversely calculated according to the capacitance-pressure mapping relationship, so as to realize accurate pressure detection.

[0034] Figure 4 The three-electrode ion electric pressure sensor of the present application and the two-electrode output curve are shown in the comparison. It can be seen that the response of the three-electrode ion electric pressure sensor of the present application is obviously higher than that of the two-electrode sensor. Figure 5 The response curve of the three-electrode ion electric pressure sensor of the present application under different pressures.

[0035] As a preferred embodiment of the present application, the thickness of the flexible electrode 2, whether single-sided electrode or double-sided electrode, needs to be controlled between 0.1-0.2mm.

[0036] Example 1: Manufacturing of three-electrode ion electric pressure sensor As shown in Figure 1 The internal layering order of the three-electrode ion electric pressure sensor is flexible electrode 2, spacer layer 3, micro-structured sensitive layer 4, flexible electrode 2, micro-structured sensitive layer 4, spacer layer 3 and flexible electrode 2 in turn.

[0037] S1, prepare flexible electrode by sputtering gold target material In this embodiment, the upper and lower two layers of flexible electrodes are both single-sided electrodes, and the middle flexible electrode is a double-sided electrode. For single-sided electrodes, it includes a flexible substrate layer 21 and a flexible conductive layer 22 located on the substrate layer. For double-sided electrodes, it includes a middle flexible substrate layer 21 and flexible conductive layers 22 distributed on both sides of the substrate.

[0038] When preparing, first, use laser cutting to make a mask plate for sputtering of the substrate and the electrode; then clean the surface of the substrate and the mask plate with alcohol and deionized water, and after high-temperature drying, fix the two together (mask plate on top) for sputtering; finally, clean the surface of the sputtered substrate with alcohol and deionized water, and dry, to complete the preparation of the single-sided electrode. The double-sided electrode is continued to be sputtered on the reverse side based on the single-sided electrode.

[0039] S2, manufacture micro-structured sensitive layer In this embodiment, the upper and lower layers of the micro-structured sensitive layer 4 adopt different scales of micro-structures, and the micro-structured sensitive layer 4 includes a bottom plate 41 and a plurality of hemispherical protrusions 42 integrally formed on the bottom plate 41. The hemispherical protrusions 42 are arranged in a rectangular array.

[0040] When prepared: the base medium material, the ionic medium material and the silicon dioxide are added according to the mass ratio, the mass ratio between the base medium material and the ionic medium material can be in the range of 20:1-2:1, and the ratio between the ionic medium material and the silicon dioxide can be in the range of 3:1-30:1. Different ratios will result in different ionization effects, and the specific ratio needs to be quantitatively analyzed according to different needs.

[0041] After the material is added, it is stirred by a magnetic stirrer, then put into a vacuum machine to remove the gas mixed in the liquid, and then the liquid is poured into a mold which is processed by a CNC process in advance, and is placed in a vacuum drying box for drying for 24 hours. The mold is taken out, and the solidified sensitive layer is separated from the mold to obtain the micro-structured sensitive layer 4.

[0042] The method for preparing a sensitive layer with different scale micro-structures is completely consistent with other processes except that the mold used is different.

[0043] S3, preparing a flexible packaging shell Take any one of polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU) and silica gel and other materials, stir by magnetic force, then inject into a 3D printing mold, vacuum dry for 24 hours until completely solidified, and then take out the mold to obtain the flexible packaging shell 1.

[0044] S4, making a spacer layer The spacer layer can be prepared by laser cutting a commercial flexible film or by a reverse mold method. The following is the implementation process of the two methods.

[0045] 1) Laser cutting method Prepare a commercial flexible film substrate, set the laser cutting pattern for cutting, and then clean it with deionized water, and then dry it at room temperature to obtain the spacer layer 3.

[0046] 2) Reverse mold method Mix the liquid flexible material, prepare the 3D printing mold, then pour the liquid material into the mold, and place it in a vacuum drying box for drying for 24 hours. After complete solidification, the mold is taken out to obtain the spacer layer 3.

[0047] S5, making a three-electrode ionization pressure sensor The flexible packaging shell 1, the flexible electrode 2, the interval layer 3 and the sensitive layer 4 with microstructure prepared in the above process are stacked in the order of layers, wherein the flexible packaging shell 1 and the flexible electrode 2, the flexible electrode 2 and the interval layer 3 are adhered by 3M double-sided adhesive, and the other layers are combined after being stacked freely.

[0048] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the present application.

Claims

1. A high-range, high-sensitivity three-electrode ionization voltage pressure sensor, characterized in that: It includes a flexible encapsulation shell and three flexible electrodes encapsulated within the flexible encapsulation shell, two microstructured sensitive layers arranged between the flexible electrodes, and a spacer layer disposed between the flexible electrodes and the microstructured sensitive layers. The flexible electrodes and the microstructured sensitive layers are arranged in a cross-stacked manner, and the two microstructured sensitive layers have sensitive layer microstructures of different scales.

2. The high-range, high-sensitivity three-electrode isolating voltage pressure sensor as described in claim 1, characterized in that: The flexible electrode includes a flexible substrate, a flexible conductive layer, and a lead wire. The lead wire is arranged on the flexible substrate and is insulated and encapsulated.

3. The high-range, high-sensitivity three-electrode isolating voltage pressure sensor as described in claim 1, characterized in that: The sensitive layer with microstructure includes a sensitive layer base plate and a sensitive layer microstructure integrally formed on the sensitive layer base plate. The sensitive layer microstructure is arranged in a rectangular array. The shape of the sensitive layer microstructure includes, but is not limited to, a dome structure, a pyramid, a cylinder, and a sandpaper structure.

4. The high-range, high-sensitivity three-electrode isolating voltage pressure sensor as described in claim 1, characterized in that: The thickness of the flexible packaging shell is controlled within 0.5 mm, and it is prepared using any one of polydimethylsiloxane, thermoplastic polyurethane, and silicone.

5. The high-range, high-sensitivity three-electrode isolating voltage pressure sensor as described in claim 1, characterized in that: The sensitive layer with microstructures is prepared by molding and 3D additive printing. One side is smooth, while the other side has densely distributed sensitive layer microstructures. The size of the sensitive layer microstructures accounts for 0.5-0.25% of the overall size of the sensor.

6. The high-range, high-sensitivity three-electrode isolating voltage force sensor as described in claim 3, characterized in that: The sensitive layer substrate is prepared from any one of polydimethylsiloxane, thermoplastic polyurethane, and polyurethane; the sensitive layer microstructure is prepared from ionic medium material and adsorbent material, wherein the ionic medium material is an imidazole ionic liquid or a pyridine ionic liquid; and the adsorbent material is boron nitride or silicon dioxide.

7. The high-range, high-sensitivity three-electrode isolating voltage pressure sensor as described in claim 3, characterized in that: The sensitive layer with microstructure is separated from the flexible electrode by spacer layers at both ends. The thickness of the spacer layers is between 0.1-0.2 mm, and they are prepared using any one of polydimethylsiloxane, thermoplastic polyurethane, and polyurethane.

8. The high-range, high-sensitivity three-electrode isolating voltage force sensor as described in claim 2, characterized in that: The flexible substrate is prepared using any one of polyimide, polyethylene terephthalate, thermoplastic polyurethane, and silicone film; the flexible conductive layer is prepared using any one of stretchable conductive silver paste, liquid metal, carbon nanotubes, graphene, carbon black, copper foil, and gold foil.

9. The method for preparing a high-range, high-sensitivity three-electrode ionization pressure sensor as described in any one of claims 1-8, characterized in that: Includes the following steps: S1. Flexible electrodes are fabricated by sputtering gold targets; S2. Fabricate a sensitive layer with a microstructure; The substrate dielectric material, ion dielectric material and silicon dioxide are mixed in a certain proportion. After the gas mixed in the liquid is removed by vacuuming, the mixture is poured into a mold, vacuum dried for 24 hours, and then demolded to obtain the final product. S3. Use 3D printing molds to prepare flexible packaging shells; S4. Use laser cutting or molding methods to create the spacer layer; S5. Fabricate a three-electrode voltage-isolation pressure sensor; The flexible packaging shell, flexible electrode, spacer layer, and microstructured sensitive layer are stacked together in the following order: flexible electrode - spacer layer - microstructured sensitive layer - flexible electrode - microstructured sensitive layer - spacer layer - flexible electrode. The flexible packaging shell and flexible electrode, as well as the flexible electrode and spacer layer, are bonded together with 3M double-sided adhesive. The other layers can be freely stacked and combined.

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