A flexible capacitive pressure sensor with contact-dominated field enhancement and its preparation method

Abstract

The present invention relates to a contact-dominated, field-enhanced flexible capacitive pressure sensor and a method for preparing the same. The contact-dominated, field-enhanced flexible capacitive pressure sensor comprises an elastomeric composite electrode and a composite dielectric layer. The elastomeric composite electrode is a composite of an elastomeric electrode and a metal electrode. The elastomeric electrode is an elastomer made of a composite material of polydimethylsiloxane and carbon nanotubes. The elastomeric electrode forms a multi-scale microstructure on the outer surface facing the composite dielectric layer. The metal electrode is a metal layer evaporated on the surface of the multi-scale microstructure. The composite dielectric layer is a composite of an inorganic metal oxide dielectric layer and an organic dielectric layer to form an upper and lower layer structure. The contact-dominated, field-enhanced flexible capacitive pressure sensor provided by the present invention has the characteristics of high sensitivity, high linear response, wide sensing range, and good mechanical stability, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of capacitive pressure sensors, and in particular to a contact-dominated field-enhanced flexible capacitive pressure sensor and a preparation method thereof. Background Art

[0002] Flexible capacitive pressure sensors are a new type of electronic device that is mechanically compliant and can be conformally attached to irregular surfaces. They can detect pressure signals by converting them into detectable capacitance changes. Compared with other types of sensors, flexible capacitive pressure sensors offer low power consumption and the ability to respond to both dynamic and static pressures. They can provide core electronic device support for emerging fields such as human-computer interaction, neural prosthetics, bionic robots, and advanced healthcare electronics. However, existing typical flexible capacitive sensors suffer from relatively low sensitivity, a relatively narrow sensing range, and low response linearity.

[0003] To solve the above problems, existing design solutions for improving flexible capacitive sensors include microstructured dielectrics and microstructured electrodes. Specifically, the microstructured dielectric design solution is to microstructure the elastomeric dielectric layer (such as polydimethylsiloxane, PDMS) between two flexible parallel plate electrodes, usually constructing a single-scale micro-pyramid structure on its surface. However, on the one hand, the single-scale microstructured dielectric layer design is prone to response saturation under large pressure, and the response is non-linear; on the other hand, the thickness of the elastomeric dielectric layer is relatively thick, which leads to relatively small changes in the electric field and capacitance, making the sensor sensitivity low and the sensing range relatively small. In addition, the elastomeric dielectric layer made of a single material usually has a low dielectric constant, which also limits the sensitivity of the sensor to a certain extent.

[0004] Microstructured electrode designs typically involve vapor-depositing a layer of metal on the surface of a single microstructured elastomer electrode or coating a mesh-like nanoconductive layer (such as carbon nanotubes, CNTs) on the surface of a single microstructured elastomer, using it as a compressible conductive electrode. However, the response of a single-scale micro-pyramid structure is prone to saturation, and the linear relationship between pressure and the change in contact area between the electrode and the dielectric layer is not strong. Furthermore, regarding electrode design, vapor-depositing only a layer of metal on the surface of the elastomer electrode microstructure often results in cracks in the metal layer under relatively small strains, causing the sensor to output unstable signals and reduce sensitivity when subjected to high pressure. While the use of a single nano-mesh conductive material can avoid cracking under high strain, the actual utilization rate of the effective conductive area of the mesh material is low, resulting in a low sensitivity sensor. Furthermore, the coated mesh material is also prone to wear. Summary of the Invention

[0005] The present invention solves the problems of existing flexible capacitor sensors in relatively low sensing sensitivity, relatively narrow sensing range, low response linearity and poor mechanical stability, and provides a flexible capacitive pressure sensor based on contact-dominated field enhancement, which can not only improve the sensitivity of the sensor, but also expand the sensing range, improve the linear response and mechanical stability.

[0006] The technical solutions to be protected by the present invention are as follows:

[0007] The present invention provides a contact-dominated field-enhanced flexible capacitive pressure sensor, comprising an elastomeric composite electrode, a composite dielectric layer, and a planar electrode. The sensor is characterized in that the elastomeric composite electrode is composed of an elastomeric electrode and a metal electrode, the elastomeric electrode is an elastomer prepared from a composite material of polydimethylsiloxane and carbon nanotubes, the elastomeric electrode forms a multi-scale microstructure on the outer surface facing the composite dielectric layer, the metal electrode is a metal layer evaporated on the outer surface of the elastomeric electrode having the multi-scale microstructure, and the composite dielectric layer is composed of an upper and lower layer structure formed by an inorganic metal oxide dielectric layer and an organic dielectric layer.

[0008] Preferably, the preparation method of the polydimethylsiloxane and carbon nanocomposite material is: mixing polydimethylsiloxane with a n-hexane solution, dispersing carbon nanotubes in isopropanol by water bath ultrasound, and finally mixing the two solutions.

[0009] Preferably, the ratio of polydimethylsiloxane to hexane solution is 1:5-1:10, the ratio of carbon nanotubes to isopropyl alcohol is 1:200, and the ratio of polydimethylsiloxane to carbon nanotubes is 100:1-100:5.

[0010] Preferably, the multi-scale microstructures are a plurality of irregular three-dimensional structures or a plurality of micro-pyramid structures of different sizes formed on the surface where the elastomer electrode contacts the composite dielectric layer.

[0011] Preferably, the metal electrode is obtained by evaporating a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomer electrode having the multi-scale microstructure by electron beam or thermal evaporation, the thickness of the titanium or chromium is 5 nm, and the thickness of the gold is 50 nm.

[0012] Preferably, the inorganic metal oxide material is aluminum oxide or yttrium oxide or other non-conductive inorganic metal oxide materials, and the organic material is polyparaxylene or polyimide or other thin film organic materials that can be thermally deposited or spin-coated.

[0013] The present invention also provides a method for preparing a contact-dominated field-enhanced flexible capacitive pressure sensor, comprising the following steps:

[0014] S1: An elastomeric electrode is prepared using a mixed solution of polydimethylsiloxane and carbon nanotubes, so that a multi-scale microstructure is formed on the outer surface of the elastomeric electrode facing the composite dielectric layer, and a metal electrode is obtained by electron beam or thermal evaporation of a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomeric electrode having the multi-scale microstructure, wherein the thickness of the titanium or chromium is 5 nm, and the thickness of the gold is 50 nm, and finally an elastomeric composite electrode composed of an elastomeric electrode and a metal electrode is obtained.

[0015] S2: Thermally deposit or spin-coat a flexible substrate material with a thickness of 1-3 μm on a low-resistance silicon wafer, evaporate a planar electrode on the flexible substrate material, deposit an inorganic metal oxide dielectric layer and an organic dielectric layer on the planar electrode, and then peel off the low-resistance silicon wafer from the flexible substrate by electrochemical etching to obtain a composite dielectric layer with a flexible substrate connected to the planar electrode.

[0016] S3: The planar electrode with a flexible substrate, the elastomer composite electrode obtained in S1, and the composite dielectric layer with a flexible substrate connected to the planar electrode obtained in S2 are assembled in sequence from top to bottom to obtain a contact-dominated field-enhanced flexible capacitive pressure sensor.

[0017] Preferably, the method for forming the multi-scale microstructure comprises drop-coating a mixed solution of polydimethylsiloxane and carbon nanotubes onto a hydrophobic substrate, evacuating the substrate and then heating and curing the mixed solution, wherein irregular microstructures are naturally formed on the surface of the mixed solution during the curing process; or etching a silicon wafer by photolithography to obtain a mold having a plurality of micro-pyramid structures of different sizes, treating the mold hydrophobically, pouring the mixed solution of polydimethylsiloxane and carbon nanotubes into the mold, evacuating the substrate, heating and curing the mixed solution, and then peeling off the mold, so that a plurality of micro-pyramid structures of different sizes are formed on the outer surface of the elastomer electrode facing the composite dielectric layer.

[0018] Preferably, the depositing of the inorganic metal oxide dielectric layer and the organic dielectric layer refers to depositing an inorganic metal oxide dielectric layer with a thickness of about 5nm-20nm by atomic deposition; or using evaporation or thermal oxidation to obtain an inorganic metal oxide dielectric layer with a thickness of 5nm-20nm on the surface of a planar electrode, and then obtaining an organic dielectric layer with a thickness of less than 1μm by thermal deposition or spin coating.

[0019] Preferably, the thickness of the organic dielectric layer is 100-200 nm.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a contact-dominated field-enhanced flexible capacitive pressure sensor, comprising an elastomeric composite electrode, a composite dielectric layer, and a planar electrode. The sensor is characterized in that the elastomeric composite electrode is composed of an elastomeric electrode and a metal electrode, the elastomeric electrode is an elastomer prepared from a composite material of polydimethylsiloxane (PDMS) and carbon nanotubes (CNTs), the elastomeric electrode forms a multi-scale microstructure on the outer surface facing the composite dielectric layer, the metal electrode is a metal layer evaporated on the outer surface of the elastomeric electrode having a multi-scale microstructure; the composite dielectric layer is composed of an upper and lower layer structure formed by an inorganic metal oxide dielectric and an organic dielectric layer. Since the elastomer composite electrode is an elastomer prepared by mixing liquids of polydimethylsiloxane (PDMS) and carbon nanotubes (CNTs), and the outer surface of the elastomer electrode with a multi-scale microstructure is vapor-deposited with a metal electrode, the carbon nanotubes form a nano-conductive network with high mechanical stability in the elastomer electrode, which can avoid the sensitivity loss caused by the breakage of a single metal electrode under large stress or strain due to the mechanical mismatch between the elastomer electrode and the metal electrode; at the same time, the metal layer electrode vapor-deposited on the outer surface of the elastomer electrode with a multi-scale microstructure can effectively increase the effective conductive area of the single nano-network structure.

[0022] The multi-scale microstructure formed on the outer surface of the elastomeric electrode facing the composite dielectric layer, on the one hand, introduces more gaps between the elastomeric composite electrode and the composite dielectric layer, reducing the initial capacitance and improving the sensitivity of the sensor; on the other hand, the smaller-sized microstructures can prevent the larger-sized microstructures from saturating prematurely, increasing the linear correlation between pressure changes and changes in the contact area between the multi-scale microstructures and the composite dielectric layer, so that the change in capacitance is dominated by contact mechanics rather than changes in the dielectric constant or electrode spacing, further increasing the sensitivity and linearity of the sensor under higher pressures and expanding the detectable pressure response range to a certain extent.

[0023] In the composite dielectric layer composed of an inorganic metal oxide dielectric layer and an organic dielectric layer, the use of an inorganic metal oxide material with a high dielectric constant can improve the contact interface between the planar metal electrode and the organic dielectric layer, improve the uniformity of the ultra-thin organic dielectric layer, and thus obtain an ultra-thin composite dielectric layer with high mechanical and electrical stability. Its ultra-thin and high dielectric constant characteristics enhance the local electric displacement field on the composite dielectric layer, that is, the electric displacement field at the interface between the multi-scale microstructure and the composite dielectric layer, thereby increasing the change in capacitance and improving the sensitivity of the sensor. At the same time, due to the enhanced local electric displacement field of the composite dielectric layer, the change in capacitance is dominated by the contact area, making the capacitance proportional to the contact area, further improving the linear correlation between pressure and response. This solves the problem of low dielectric constant and thick thickness of elastomeric dielectrics in microstructured dielectric design schemes and poor mechanical and electrical stability of dielectric layers of single materials in microstructured electrode design schemes, which reduces sensor sensitivity, stability and linearity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : Flexible capacitive pressure sensor with contact-dominated field enhancement before pressure application.

[0025] Figure 2 : Flexible capacitive pressure sensor with contact-dominated field enhancement after applied pressure. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the flexible capacitive pressure sensor with contact-dominated field enhancement proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structure, proportion, size, etc. shown in the drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the implementation conditions of the present invention, so they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0027] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. The present invention provides a flexible capacitive pressure sensor with contact-dominated field enhancement, such as Figure 1 and Figure 2As shown, it includes: an elastomer composite electrode 1: an elastomer electrode 11 composed of a composite material, a multi-scale microstructure 12 formed on the outer surface of the elastomer electrode facing the composite dielectric layer, and a metal electrode 13 composed of a metal layer evaporated on the outer surface of the elastomer electrode 11 having the multi-scale microstructure 12; a composite dielectric layer 2: an organic dielectric layer 21, an inorganic metal oxide dielectric layer 22; a planar electrode 3: a metal electrode 31, and a flexible substrate 32 connected to the metal electrode.

[0028] In some embodiments of the present invention, the contact-dominated field-enhanced flexible capacitive pressure sensor includes an elastomeric composite electrode 1, a composite dielectric layer 2 and a planar electrode 3, characterized in that the elastomeric composite electrode 1 includes an elastomeric electrode 11 and a metal electrode 13, the elastomeric electrode 11 is an elastomeric electrode prepared from a composite material of polydimethylsiloxane and carbon nanotubes, the elastomeric electrode 11 forms a multi-scale microstructure 12 on the outer surface facing the composite dielectric layer, and the metal electrode is a metal layer 13 evaporated on the outer surface of the elastomeric electrode 11 having the multi-scale microstructure 12; the composite dielectric layer 2 is composed of an inorganic metal oxide dielectric layer 22 and an organic dielectric layer 21 to form an upper and lower layer structure; in some embodiments of the present invention, the planar electrode 3 is a metal electrode made of a titanium-gold alloy, the thickness of the titanium is 5 nm, and the thickness of the gold is 50 nm; in other embodiments of the present invention, the planar electrode 3 is a metal electrode made of a chromium-gold alloy, the thickness of the chromium is 5 nm, and the thickness of the gold is 50 nm. In some other embodiments of the present invention, the planar electrode includes a metal electrode 31 and a flexible substrate 32 .

[0029] In some embodiments of the present invention, the preparation method of the polydimethylsiloxane (PDMS) and carbon nanotube (CNT) composite material used to prepare the elastomer electrode 11 is: mixing polydimethylsiloxane (PDMS) with a hexane solution, dispersing the carbon nanotube (CNT) in isopropanol by water bath ultrasound, and finally mixing the two solutions.

[0030] In some embodiments of the present invention, the ratio of polydimethylsiloxane (PDMS) to hexane solution is 1:5-1:10, the ratio of carbon nanotubes (CNT) to isopropyl alcohol is 1:200, and the ratio of polydimethylsiloxane (PDMS) to carbon nanotubes (CNT) is 100:1-100:5.

[0031] In some embodiments of the present invention, the multi-scale microstructure 12 formed on the surface of the elastomeric electrode 11 in contact with the composite dielectric layer 2 is a plurality of irregular three-dimensional structures; in other embodiments of the present invention, the multi-scale microstructure 12 formed on the outer surface of the elastomeric electrode 11 facing the composite dielectric layer 2 is a plurality of micro-pyramid structures of different sizes.

[0032] In some embodiments of the present invention, the metal electrode 13 in the elastomer composite electrode 1 is a metal layer deposited on the outer surface of the elastomer electrode 1 having the multi-scale microstructure 12 by electron beam evaporation; in other embodiments of the present invention, the metal electrode 13 in the elastomer composite electrode 1 is a metal layer deposited on the outer surface of the elastomer electrode 1 having the multi-scale microstructure 12 by thermal evaporation; in some embodiments of the present invention, the metal electrode is formed by evaporating a titanium-gold alloy, the thickness of the titanium is 5 nm, and the thickness of the gold is 50 nm; in other embodiments of the present invention, the metal electrode is formed by evaporating a chromium-gold alloy, the thickness of the chromium is 5 nm, and the thickness of the gold is 50 nm.

[0033] In some embodiments of the present invention, the inorganic metal oxide dielectric layer 22 in the composite dielectric layer 2 is made of aluminum oxide; in some embodiments of the present invention, the inorganic metal oxide dielectric layer 22 in the composite dielectric layer 2 is made of yttrium oxide; in some embodiments of the present invention, the organic dielectric layer 21 is made of parylene; in other embodiments of the present invention, the organic dielectric layer 21 is made of polyimide (PI).

[0034] In some embodiments of the present invention, the preparation method of the contact-dominated field-enhanced flexible capacitive pressure sensor comprises the following steps: S1: preparing an elastomeric electrode 1 using a mixed solution of polydimethylsiloxane and carbon nanotubes, forming a multi-scale microstructure 12 on the outer surface of the composite dielectric layer 2 with the elastomeric electrode 11, and obtaining a metal electrode 13 by electron beam or thermal evaporation of a metal layer on the outer surface of the elastomeric electrode having the multi-scale microstructure 12, thereby obtaining an elastomeric composite electrode composed of an elastomeric electrode and a metal electrode. S2: thermally depositing or spin-coating a flexible substrate material 31 with a thickness of 1-3 μm on a low-resistance silicon wafer, evaporating a planar electrode 3 on the flexible substrate material, depositing an inorganic metal oxide dielectric layer 22 and an organic dielectric layer 21 on the planar electrode 32, and then peeling off the low-resistance silicon wafer by electrochemical etching to obtain a composite dielectric layer 2 connected to the planar electrode 3 having a flexible substrate 31. S3: The planar electrode 3 with a flexible substrate 31, the elastomeric composite electrode 1 obtained in S1, and the composite dielectric layer 2 connected to the planar electrode 32 with a flexible substrate 31 obtained in S2 are assembled in sequence from top to bottom to obtain a flexible capacitive pressure sensor with contact-dominated field enhancement.

[0035] In some embodiments of the present invention, the method for forming the multi-scale microstructure 21 is to drop-coat a mixed solution of polydimethylsiloxane (PDMS) and carbon nanotubes (CNT) onto a hydrophobic substrate, evacuate the solution, and heat and solidify it. During the curing process, an irregular microstructure is naturally formed on the surface of the mixed solution. In other embodiments of the present invention, the method for forming the multi-scale microstructure 21 is to etch a silicon wafer by photolithography to obtain a mold having several micro-pyramid structures of different sizes. After the mold is hydrophobicized, the mixed solution of polydimethylsiloxane (PDMS) and carbon nanotubes (CNT) is poured into the mold and evacuated. After heating and solidifying, the mold is peeled off, so that the elastomer electrode 11 faces the outer surface of the composite dielectric layer 2 to form several micro-pyramid structures of different sizes.

[0036] In some embodiments of the present invention, the depositing of the inorganic metal oxide dielectric layer 22 and the organic dielectric layer 21 refers to depositing an inorganic metal dielectric layer with a thickness of about 5nm-20nm on a planar electrode by atomic deposition, and then thermally depositing or spin-coating an organic dielectric layer with a thickness of less than 1μm on the surface of the inorganic metal oxide dielectric layer; in other embodiments of the present invention, the depositing of the inorganic metal oxide dielectric layer 22 and the organic dielectric layer 21 refers to obtaining an inorganic metal dielectric layer with a thickness of 5nm-20nm on the surface of a planar electrode by evaporation or thermal oxidation, and then thermally depositing or spin-coating an organic dielectric layer with a thickness of less than 1μm on the surface of the inorganic metal oxide dielectric layer.

[0037] Attachment Figure 2 A schematic diagram of the contact-dominated field-enhanced flexible capacitive pressure sensor provided by the present invention under pressure. External pressure acts on a planar electrode 3 and is thereby transmitted to an elastomeric composite electrode 1 connected to the planar electrode 3, causing the elastomeric composite electrode 1 to contact a composite dielectric layer 2. Because the elastomeric electrode 11 forms a multi-scale microstructure 12 on its outer surface facing the composite dielectric layer 2, when the pressure applied to the planar electrode 3 is low, the contact area between the elastic electrode 1 and the composite dielectric layer 2 is also small. This prevents capacitance saturation in the sensor when pressure is low, increases the linear correlation between pressure changes and changes in the contact area between the multi-scale microstructure and the composite dielectric layer, and enables capacitance changes to be dominated by contact mechanics rather than changes in the dielectric constant or electrode spacing. This further increases the sensitivity of the sensor and expands the detectable pressure response range to a certain extent.

[0038] The elastomer electrode 11 is made of a composite material of polydimethylsiloxane (PDMS) and carbon nanotubes (CNTs), so the carbon nanotubes (CNTs) form a nano-conductive network with high mechanical stability in the elastomer electrode, thereby enhancing the mechanical stability of the elastomer electrode 11. The metal electrode 13 composed of a metal layer evaporated on the outer surface of the elastomer composite electrode 1 having a multi-scale microstructure 12 can effectively increase the effective conductive area of a single nano-network structure. The carbon nanotubes (CNTs) in the elastomer electrode 11 can avoid the decrease in sensitivity caused by the breakage of the metal electrode 13 under large stress or strain due to the mechanical mismatch between the elastomer electrode 11 and the metal electrode 13 composed of the metal layer.

[0039] The composite dielectric layer 2 is composed of an organic dielectric layer 21 and an inorganic metal oxide dielectric layer 22. The composite use of organic and inorganic materials solves the problem that the dielectric layer thickness is usually large and the relative dielectric constant is low when a single organic elastomer material is used as the dielectric layer in the microstructured dielectric design scheme, and the problem that the mechanical and electrical stability of the single inorganic metal oxide material used as the dielectric layer in the microstructured electrode design scheme is poor. Due to the characteristics of ultra-thin thickness and / or high dielectric constant, the composite dielectric layer 2 can enhance the local electric displacement field in this device configuration, that is, the electric displacement field on the contact surface between the elastomer electrode 1 and the composite dielectric layer 2, thereby increasing the change in capacitance and improving the sensitivity of the sensor. At the same time, the design characteristics of ultra-thin thickness and high dielectric constant of the composite dielectric layer 2 make the capacitance of the sensor dominated by the capacitance of the contact surface, making the capacitance proportional to the contact area, thereby further improving the linearity of the pressure response.

[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-described embodiment merely represents one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A contact-dominated field-enhanced flexible capacitive pressure sensor comprising an upper planar electrode, an elastomer composite electrode, a composite dielectric layer, and a lower planar electrode, characterized in that The elastomer composite electrode is composed of an elastomer electrode and a metal electrode. The elastomer electrode is an elastomer prepared from a composite material of polydimethylsiloxane and carbon nanotubes. The elastomer electrode forms a multi-scale microstructure on the outer surface facing the composite dielectric layer. The metal electrode is a metal layer evaporated on the outer surface of the elastomer electrode with a multi-scale microstructure. The composite dielectric layer is composed of an upper and lower layer structure formed by an inorganic metal oxide dielectric layer and an organic dielectric layer.

2. The contact-dominated field-enhanced flexible capacitive pressure sensor according to claim 1, characterized in that The preparation method of the polydimethylsiloxane and carbon nanocomposite material comprises the following steps: mixing polydimethylsiloxane with a n-hexane solution, dispersing carbon nanotubes in isopropyl alcohol by water bath ultrasound, and finally mixing the two solutions.

3. The contact-dominated field-enhanced flexible capacitive pressure sensor according to claim 2, characterized in that The ratio of the polydimethylsiloxane to the n-hexane solution is 1:5-1:10, the ratio of the carbon nanotubes to the isopropyl alcohol is 1:200, and the ratio of the polydimethylsiloxane to the carbon nanotubes is 100:1-100:

5.

4. The contact-dominated field-enhanced flexible capacitive pressure sensor according to claim 1, characterized in that The multi-scale microstructures are a plurality of irregular three-dimensional structures or a plurality of micro-pyramid structures of different sizes formed on the surface where the elastomer electrode contacts the composite dielectric layer.

5. The contact-dominated field-enhanced flexible capacitive pressure sensor according to claim 1, characterized in that The metal electrode is obtained by evaporating a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomer electrode having the multi-scale microstructure by electron beam or thermal evaporation. The thickness of the titanium or chromium is 5 nm, and the thickness of the gold is 50 nm.

6. The contact-dominated field-enhanced flexible capacitive pressure sensor according to claim 1, characterized in that The inorganic metal oxide material is aluminum oxide or yttrium oxide or other non-conductive inorganic metal oxide materials, and the organic material is parylene or polyimide or other thin film organic materials that can be thermally deposited or spin-coated.

7. A method for preparing a contact-dominated field-enhanced flexible capacitive pressure sensor, comprising the following steps: S1: preparing an elastomeric electrode using a mixed solution of polydimethylsiloxane and carbon nanotubes, forming a multi-scale microstructure on the outer surface of the elastomeric electrode facing the composite dielectric layer, and depositing a titanium-gold alloy or a chromium-gold alloy on the outer surface of the elastomeric electrode having the multi-scale microstructure by electron beam or thermal evaporation to obtain a metal electrode, wherein the thickness of the titanium or chromium is 5 nm and the thickness of the gold is 50 nm, to finally obtain an elastomeric composite electrode composed of the elastomeric electrode and the metal electrode; S2: thermally depositing or spin-coating a flexible substrate material with a thickness of 1-3 μm on a low-resistance silicon wafer, evaporating a planar electrode on the flexible substrate material, depositing an inorganic metal oxide dielectric layer and an organic dielectric layer on the planar electrode, and then peeling the low-resistance silicon wafer from the flexible substrate by electrochemical etching to obtain a composite dielectric layer having a flexible substrate and connected to the planar electrode; S3: The planar electrode with a flexible substrate, the elastomer composite electrode obtained in S1, and the composite dielectric layer with a flexible substrate connected to the planar electrode obtained in S2 are assembled in sequence from top to bottom to obtain a contact-dominated field-enhanced flexible capacitive pressure sensor.

8. The preparation method according to claim 7, characterized in that The method for forming the multi-scale microstructure comprises: drop-coating a mixed solution of polydimethylsiloxane and carbon nanotubes onto a hydrophobic substrate, evacuating the substrate, and then heating and curing the mixed solution. During the curing process, the mixed solution naturally forms irregular microstructures on the surface. Alternatively, a silicon wafer is etched by photolithography to obtain a mold having a plurality of micro-pyramid structures of different sizes. After the mold is hydrophobicized, the mixed solution of polydimethylsiloxane and carbon nanotubes is poured into the mold, evacuated, heated, and cured. The mold is then peeled off, so that a plurality of micro-pyramid structures of different sizes are formed on the outer surface of the elastomer electrode that contacts the composite dielectric layer.

9. The preparation method according to claim 7, characterized in that The depositing of the inorganic metal oxide dielectric layer and the organic dielectric layer refers to depositing an inorganic metal oxide dielectric layer with a thickness of about 5nm-20nm by atomic deposition; or using evaporation or thermal oxidation to obtain an inorganic metal oxide dielectric layer with a thickness of 5nm-20nm on the surface of a planar electrode, and then obtaining an organic dielectric layer with a thickness of less than 1μm by thermal deposition or spin coating.

10. The preparation method according to claim 9, characterized in that The thickness of the organic dielectric layer is 100-200 nm.

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