CN116558676A

CN116558676A - Capacitive pressure sensor, array sensor and preparation method

Info

Publication number: CN116558676A
Application number: CN202310538645.XA
Authority: CN
Inventors: 胡雪丰; 杨泽宇; 郭仪; 廖方骐
Original assignee: Chengdu Rotex Technology Co ltd
Current assignee: Chengdu Rotex Technology Co ltd
Priority date: 2023-05-12
Filing date: 2023-05-12
Publication date: 2023-08-08

Abstract

The embodiment of the application provides a capacitive pressure sensor, an array sensor and a preparation method, and relates to the field of sensors. The capacitive pressure sensor comprises a first electrode layer, a dielectric layer and a second electrode layer which are sequentially stacked, wherein the dielectric layer contains conductive filler, the conductive filler comprises at least one of nonmetal conductive filler, conductive oxide filler and semiconductor filler, and an insulating layer is further arranged between the first electrode layer or the second electrode layer and the dielectric layer. The array type sensor comprises a plurality of capacitive pressure sensors, all the capacitive pressure sensors are horizontally arranged and distributed, and electrode layers with the same polarity in all the capacitive pressure sensors are connected through a circuit and led out to the outside. The sensor has high sensitivity, wide pressure bearing value range and strong stability.

Description

Capacitive pressure sensor, array sensor and preparation method

Technical Field

The application relates to the field of sensors, in particular to a capacitive pressure sensor, an array sensor and a preparation method.

Background

The flexible pressure sensor has the advantages of being easy to bend, light in weight and durable, and can be used for easily detecting the pressure of a curved object compared with the traditional pressure sensor, and is particularly suitable for measuring the distribution pressure of the surface of a human body, so that the flexible pressure sensor is widely applied to the fields of robot electronic skin, human health detection, human-computer interaction and the like.

In addition, the pressure sensor can be divided into a piezoresistive pressure sensor, a capacitive pressure sensor and a piezoelectric pressure sensor according to the measurement signal types, wherein the capacitive pressure sensor has the characteristics of low power consumption, high precision and good dynamic response, and is suitable for being applied to mobile electronic equipment and occasions with higher precision requirements.

The existing flexible capacitive pressure sensor mainly comprises two flexible electrode layers and a flexible dielectric layer positioned between the two electrode layers, wherein the dielectric layer is made of a high-elasticity dielectric material, the electrode layer is made of a conductive material, and the capacitance of the sensor is determined by the dielectric constant, the area and the thickness of the dielectric layer. The sensor has low sensitivity, small detection range, easy influence of electromagnetic interference and the like, and has poor detection effect on small touch feeling and small pressure related to items such as light operation in daily activities.

Therefore, how to improve the sensitivity of such a sensor is a technical problem to be solved.

Disclosure of Invention

The embodiment of the application aims to provide a capacitive pressure sensor, an array sensor and a preparation method, wherein the sensor is high in sensitivity, wide in pressure bearing value range and high in stability.

In a first aspect, embodiments of the present application provide a device including a first electrode layer, a dielectric layer, and a second electrode layer that are sequentially stacked, where the dielectric layer contains a conductive filler, and the conductive filler includes at least one of a non-metallic conductive filler, a conductive oxide filler, and a semiconductor filler, and an insulating layer is further disposed between the first electrode layer or the second electrode layer and the dielectric layer.

In the technical scheme, the first electrode layer and the second electrode layer are used for connecting an external circuit, conductive filler is added in the dielectric layer between the first electrode layer and the second electrode layer, and an insulating layer is arranged on one side of the dielectric layer, so that the sensor is high in sensitivity, wide in bearing value range, low in breakdown risk and high in stability.

Specifically, after the conductive filler is introduced into the dielectric layer, the dielectric constant of the material of the dielectric layer is greatly improved, and the distance between the conductive filler particles is compressed under the condition that the material of the dielectric layer is compressed, so that the dielectric constant is further improved, the capacitance value becomes obvious, and the monitoring of the pressure change response of the sensor is facilitated. If a metal filler is added, the response sensitivity is also affected because the metal filler particles cannot be made as small as the non-metal filler particles, and the metal is heavier and also tends to sink during dispersion, thus the dispersibility is poor.

In addition, according to the seepage theory, when the dielectric layer material is compressed, the seepage threshold value is reached, the material has metal characteristics, and the material cannot be used as the dielectric layer to appear on the capacitive pressure sensor. Moreover, the insulating layer is only arranged on one side of the dielectric layer, the whole structure is simple, the cost is low, the risk of capacitor breakdown can be reduced, meanwhile, the problem of capacitive reduction caused by increasing the distance between the first electrode layer and the second electrode layer due to the arrangement of too many insulating layers (the capacitance value is related to the distance between the two electrodes) is reduced, and the sensitivity of the sensor is further ensured.

In one possible implementation, the porosity of the dielectric layer is 30% -99%.

In the technical scheme, the dielectric layer of the sensor is of a porous structure, the compressibility of the sensor is enhanced, on one hand, the lifting multiple of the capacitance value is enlarged, on the other hand, due to the introduction of air, air with low dielectric constant in the compression process can be discharged when the dielectric layer is extruded, the dielectric constant is changed, the capacitance of the capacitor is changed, and the sensitivity and the response range of the sensor can be further improved.

In one possible implementation, the dielectric layer includes an elastomeric layer and a conductive filler dispersed in the elastomeric layer.

In the above technical scheme, the dielectric constant of the elastic material is better in compression and rebound resilience, so that the pressure change response efficiency of the capacitive pressure sensor can be ensured, the pressure change sensitivity in the compression process can be ensured by the good compression property, and the rebound resilience can ensure that the structure of the capacitive pressure sensor is recovered when the pressure disappears, so that the sensor can be effectively used for a long time.

In one possible implementation, the non-metallic conductive filler is selected from at least one of carbon nanotubes, graphene, carbon powder, PEDOT polymer, polyaniline (PANI), polythiophene (PTh), polystyrene sulfonate (PSS), and polycarbazole (PCz); the conductive oxide filler is at least one selected from copper oxide, iron oxide, tin oxide, tungsten oxide and manganese oxide; the semiconductor filler is selected from at least one of silicon, germanium, cadmium selenide, gallium arsenide, germanium arsenide, and gallium nitride.

In the technical scheme, the carbon-based material and the like are adopted as the nonmetallic conductive filler, so that the dielectric constant of the dielectric layer can be effectively increased, the conductivity of the dielectric layer can be controlled, the dielectric performance of the dielectric layer can be ensured, and the electric conductivity of the dielectric layer can not be too high.

In one possible implementation, the thickness of the dielectric layer is 0.1mm-10mm.

In one possible implementation, the insulating layer is made of at least one of PMMA, PI, PE, PET, PPS, PU, FEP, PFA, ETFE, PEEK, polysilazane, alumina, quartz, an organic polymer, polycarbonate, silicone, a fluoride material, rubber, ceramic, a high molecular polymer, and silicon dioxide.

In one possible implementation, the thickness of the insulating layer is 10nm-50 μm.

In the above technical scheme, the thinner the thickness of the insulating layer is theoretically, the better, the thinner the insulating layer has larger capacitance value, but in order to ensure the practical use effect, the risk of breakdown of the capacitor in the use process and the condition of easy breakage in the use process are prevented, and the thickness of the insulating layer cannot be too thin, so that the thickness of the insulating layer is controlled to be 10nm-50 μm.

In one possible implementation manner, the semiconductor device further comprises a buffer layer surrounding the dielectric layer, wherein the buffer layer is made of an insulating material, and the thickness range of the dielectric layer is within the thickness range of the buffer layer.

Optionally, the elastic modulus of the buffer layer is not less than the elastic modulus of the dielectric layer.

Optionally, the material of the buffer layer is at least one selected from sponge, foam cotton, PET, PMMA and rubber.

In the technical scheme, the buffer layer has the function of ensuring the rebound resilience and the structural stability of the dielectric layer, the buffer layer is arranged around the dielectric layer, the elastic modulus of the buffer layer is not less than that of the dielectric layer, the buffer layer can ensure the rebound resilience of the dielectric layer, can ensure the rapid rebound of the dielectric layer after being compressed in the long-term use process, and has good deformation recovery property; the thickness range of the buffer layer is larger than or equal to that of the dielectric layer, so that the influence of related structures such as the packaging layer on the pressure action of the dielectric layer on the stability of the overall structure of the sensor is prevented, the fact that the packaging related structures are extruded to the dielectric layer is guaranteed, the integrity of the static structure of the dielectric layer can be guaranteed as much as possible, and the response sensitivity of the dielectric layer is guaranteed.

In one possible implementation, the first electrode layer is made of a metal or nonmetal conductive material, and the second electrode layer is made of a metal or nonmetal conductive material;

optionally, the metal is selected from at least one of aluminum, copper, silver, gold, molybdenum, tungsten, and nickel; the nonmetallic conductive material is selected from at least one of conductive colloid and carbon-based material.

In one possible implementation, the first electrode layer has a thickness of 20nm-2000 μm and the second electrode layer has a thickness of 20nm-2000 μm.

In the technical scheme, the flexible electrode layer can be formed by adopting the flexible metal layer or the flexible conductive colloid layer and the like, so that the flexible sensor is constructed, and the deformation response of the sensor can be realized in multiple dimensions under the structure of adopting the flexible conductive colloid layer as the electrode layer.

In a second aspect, an embodiment of the present application provides an array sensor, which includes a plurality of capacitive pressure sensors provided in the first aspect, where all the capacitive pressure sensors are disposed horizontally and dispersedly, and electrode layers with the same polarity in all the capacitive pressure sensors are connected through a circuit and led out to the outside.

In the technical scheme, the flexible capacitive pressure sensor is used as a sensing unit of the array sensor, has strong stability, is bending-resistant and has long service life; the array sensor can adopt a form of dispersing and arranging each unit, can also adopt a form of combining each unit together and packaging, has good repeatability, is suitable for large-area use, can be applied to pressure monitoring bedding, can sense the long-term pressure condition of a human body part, can make adjustment in time, can avoid health problems such as long bedsores, and can also be applied to other fields needing to use pressure monitoring.

In one possible implementation, all capacitive pressure sensors are encapsulated by an encapsulation layer, with through holes opening around the dielectric layer.

In the technical scheme, all the capacitive pressure sensors are packaged into a whole, and the formed array type sensor has strong integrity; the through holes can be used for reducing the mutual pulling/pulling acting force between the sensing units in the use process layer, so that the reliability of the response sensitivity of the sensing units is ensured.

In a third aspect, embodiments of the present application provide a method for manufacturing a capacitive pressure sensor provided in the first aspect, where the first electrode layer, the dielectric layer, the insulating layer, and the second electrode layer are sequentially stacked and bonded together.

In the technical scheme, the preparation cost is low, and the preparation process is simple.

In one possible implementation, a first electrode layer and a second electrode layer are formed, and an insulating layer is formed on the second electrode layer; and attaching one side of the dielectric layer to the first electrode layer, and laminating and combining one side of the dielectric layer, which is away from the first electrode layer, with one side of the insulating layer, which is away from the second electrode layer.

In one possible implementation, a buffer layer is provided, and the buffer layer is disposed in a circumferential direction of the dielectric layer; the buffer layer is pressed or adhered between any combination of layers on one side of the dielectric layer close to the first electrode layer and layers on one side of the dielectric layer away from the first electrode layer.

In one possible implementation, a conductive adhesive is used to bond the first electrode layer on one side of the dielectric layer, to bond the insulating layer on the other side of the dielectric layer, and to laminate all layers together.

In one possible implementation manner, the first electrode layer, the second electrode layer and the dielectric layer in the capacitive pressure sensor are all resin polymer layers, and the preparation method comprises the following steps:

soaking the first electrode layer, the second electrode layer and the dielectric layer in a swelling solution for swelling treatment;

and stacking the first electrode layer, the dielectric layer, the insulating layer and the second electrode layer after swelling treatment, and bonding the layers together by pressing.

In the technical scheme, each glue layer of the first electrode layer, the second electrode layer and the dielectric layer is swelled, so that swelling solution enters each glue layer and is pressed, the glue layers are combined together in a chemical bonding mode, the distance between the first electrode layer and the second electrode layer is not increased, and the overall stability is good.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a capacitive pressure sensor according to a first embodiment;

FIG. 2 is a schematic view of the structure of FIG. 1 from another perspective;

FIG. 3 is a schematic structural diagram of a capacitive pressure sensor according to a second embodiment;

FIG. 4 is a schematic view of the packaged structure of FIG. 3;

FIG. 5 is a schematic structural diagram of a capacitive pressure sensor according to a third embodiment;

FIG. 6 is a schematic view of the packaged structure of FIG. 5;

FIG. 7 is a schematic diagram of an array sensor according to a fourth embodiment;

FIG. 8 is a schematic view of the structure of FIG. 7 from another perspective;

FIG. 9 is a schematic structural diagram of an array sensor according to a fifth embodiment;

fig. 10 is a schematic structural diagram of an array sensor according to a sixth embodiment;

FIG. 11 is a graph showing a pressure response of a capacitive pressure sensor according to the first embodiment;

FIG. 12 is a graph of pressure response of capacitive pressure sensors with different dielectric layers;

FIG. 13 is a graph of pressure response of capacitive pressure sensors of different layer structures.

Icon: 1-a first electrode layer; a 2-dielectric layer; 3-a second electrode layer; 4-an insulating layer; 5-a first insulating film; 6-a first encapsulation film; 7-a second insulating film; 8-a first wire; 9-a buffer layer; 10-a second wire; 11-a first connection terminal; 12-a second connection terminal; 13-through holes; 14-a second encapsulation film.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Accordingly, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present application, it should be noted that, the terms "upper," "lower," "inner," "outer," and the like indicate an orientation or a positional relationship based on the orientation or the positional relationship shown in the drawings, or an orientation or a positional relationship conventionally put in use of the product of the application, merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

First embodiment

Referring to fig. 1 and 2, the present embodiment provides a capacitive pressure sensor, which is designed as a flexible sensor, and specifically includes a first insulating film 5, a first electrode layer 1, a dielectric layer 2, an insulating layer 4, a second electrode layer 3 and a second insulating film 7, which are sequentially stacked from top to bottom, and a buffer layer 9 is further disposed around the dielectric layer 2. In other embodiments, the insulating layer 4 may also be arranged between the electrode layer and the dielectric layer 2, i.e. the insulating layer 4 is arranged between the first electrode layer 1 or the second electrode layer 3 and the dielectric layer 2.

The first electrode layer 1 and the second electrode layer 3 are flexible electrode layers made of metal or nonmetal conductive materials, specifically metal electrode layers formed by at least one of metals such as aluminum, copper, silver, gold, molybdenum, tungsten, nickel and the like, or nonmetal electrode layers made of at least one of nonmetal conductive materials such as conductive colloid, carbon-based materials and the like. The thickness of the first electrode layer 1 and the second electrode layer 3 is 20nm to 2000 μm. The materials and thicknesses of the first electrode layer 1 and the second electrode layer 3 may be the same or different. In this embodiment, the thickness of the first electrode layer 1 and the second electrode layer 3 is 10 μm.

The dielectric layer 2 comprises a porous elastic material layer and conductive filler dispersed in the porous elastic material layer, and the porosity of the dielectric layer 2 is 30% -99%, optionally 60% -95%, and the higher the porosity of the dielectric layer 2 is theoretically better under the premise of ensuring the structural integrity and stability, because the higher the porosity means that the higher the compressibility can be, so that the capacitance of the sensor can be changed to a larger extent. In an embodiment of the present application, the conductive filler includes at least one of a nonmetallic conductive filler, a conductive oxide filler, and a semiconductor filler. The nonmetallic conductive filler is generally selected from carbon-based materials such as carbon nanotubes, graphene, carbon powder, etc., and at least one of PEDOT polymer, polyaniline (PANI), polythiophene (PTh), polystyrene sulfonate (PSS), and polycarbazole (PCz); the conductive oxide filler is at least one selected from copper oxide, iron oxide, tin oxide, tungsten oxide and manganese oxide; the semiconductor filler is selected from at least one of silicon, germanium, cadmium selenide, gallium arsenide, germanium arsenide, and gallium nitride.

The thickness of the dielectric layer 2 may be 0.1mm-10mm. In this embodiment, the dielectric layer 2 is a conductive porous nanocomposite material made by compounding a nonmetallic conductive filler (carbon nanotubes and carbon powder) and silica gel, and has a porosity of 86% and a thickness of 0.7mm.

As an embodiment, the dielectric layer 2 may be prepared by the following preparation method:

s1, mixing a liquid prepolymer for forming an elastomer, a curing agent, a solvent and conductive filler and soluble particles to form a mixture. The liquid prepolymer, the curing agent, the solvent and the conductive filler may be prepared into a mixed solution and then mixed with the soluble particles to form a mixture, or the mixed solution may be semi-cured and then mixed with the soluble particles to form a mixture, which is not particularly limited in this application.

S2, solidifying the liquid prepolymer in the mixture under the action of a solidifying agent to form an elastomer, so as to obtain a semi-finished product.

And S3, removing soluble particles in the semi-finished product to obtain the dielectric layer 2.

In this embodiment, the specific preparation process of the dielectric layer 2 is as follows:

and P1, adding the carbon nano tube and the carbon powder into butanone solution, and stirring by ultrasonic to uniformly disperse the carbon nano tube and the carbon powder in a solvent to obtain a mixed solution I.

And P2, adding uncured silica gel A (the silica gel is divided into AB glue, and the main agent is added here) into the first mixed solution obtained in the step P1, and stirring to uniformly disperse the carbon nano tube and the carbon powder in the silica gel to obtain a second mixed solution.

And P3, heating the mixed solution II obtained in the step P2, and stirring simultaneously to volatilize butanone partially.

And P4, adding silica gel B for curing into the mixed solution II obtained in the step P3, and continuously stirring and uniformly mixing by utilizing ultrasonic waves to obtain a mixed solution III.

And P5, placing the soluble particles into a container, and fully mixing the mixed solution III obtained in the step P4 and coating the soluble particles to obtain a mixture I.

And P6, drying and curing the mixture obtained in the step P5 to completely cure the silica gel, and volatilizing the residual butanone.

And P7, demolding to obtain a semi-finished product.

And P8, putting the semi-finished product prepared in the step P7 into a solvent, completely ablating soluble particles, and removing water after cleaning with clear water to obtain the dielectric layer 2 with the micropore structure.

The insulating layer 4 is made of an insulating film material, and the material may be: at least one of PMMA (polymethyl methacrylate), PI (polyimide), PE (polyethylene), PET (polyethylene terephthalate), PPS (special engineering plastic), PU, FEP, PFA, ETFE, PEEK, polysilazane, alumina, quartz, an organic polymer, polycarbonate, silicone, a fluoride material, rubber, ceramic, a high molecular polymer, silica, and the like, and the thickness of the insulating layer 4 may be 10nm to 50 μm. In this embodiment, the insulating layer 4 is a PPS film having a thickness of 2. Mu.m.

The buffer layer 9 is made of insulating elastic materials such as sponge, foam cotton, PET, PMMA, rubber and the like, the elastic modulus of the buffer layer 9 is usually not smaller than the elastic modulus of the dielectric layer 2, and can be smaller than the elastic modulus of the dielectric layer 2, even not have elasticity, and the buffer layer 9 is at least arranged at two ends of the dielectric layer 2 or arranged around the dielectric layer 2. The buffer layer 9 is also located between the first insulating film 5 and the second insulating film 7, the thickness range of the dielectric layer 2 is within the thickness range of the buffer layer 9, and the buffer layer 9 plays a supporting role on the dielectric layer 2. Specifically, the buffer layer 9 is located between any combination of layers above the dielectric layer 2 and layers below the dielectric layer 2, such as: the buffer layer 9 is located between the first electrode layer 1 and the insulating layer 4, or between the first electrode layer 1 and the second electrode layer 3, or between the first insulating film 5 and the insulating layer 4, or between the first insulating film 5 and the second electrode layer 3, etc., and it is necessary to ensure that at least a partial area around the dielectric layer 2 is completely protected. In this embodiment, the buffer layer 9 is a sponge layer, and is disposed around two ends of the dielectric layer 2 and between the first insulating film 5 and the second insulating film 7.

The first insulating film 5 and the second insulating film 7 serve as substrate films for forming electrode layers, can also play a role of packaging, and can select common insulating materials such as PET (polyethylene terephthalate), PI (polyimide), PU (polyurethane), PVC (polyvinyl chloride), PPS (special engineering plastics) and the like according to the use scene of the sensor. In this embodiment, the first insulating film 5 and the second insulating film 7 are PU films having a thickness of 100. Mu.m. In the present embodiment, the first insulating film 5 and the second insulating film 7 are used as a substrate layer used in packaging or production and preparation processes, which is not an essential structure in the structure of the pressure sensor, and in other embodiments, the first insulating film 5 and/or the second insulating film 7 may be omitted.

In this embodiment, the interfaces to be connected, such as the first electrode layer 1, the dielectric layer 2 and the insulating layer 4, are all connected by bonding, and specifically, conductive adhesive glue can be used for bonding, so that the interfaces are well bonded, and the overall deformation consistency of the sensor in the subsequent press deformation process can be further ensured to be good. The buffer layer 9 may be attached to the mounting interface using double sided tape or other conventional attachment means.

The capacitive pressure sensor in this embodiment is a flexible sensor, and therefore each layer of the sensor has the following structure: the first insulating film 5, the first electrode layer 1, the dielectric layer 2, the insulating layer 4, the second electrode layer 3, and the second insulating film 7 each have a certain flexibility.

Since the thickness of the sensor is mainly determined by the thickness of the dielectric layer, the thickness of the dielectric layer needs to consider the application scene of the whole sensor, for example, a flexible sensor applied to a human body or a robot is not too thick, and in addition, the too thick sensor can influence the flexibility of the sensor. In other applications, the capacitive pressure sensor can also be designed as a rigid sensor.

In addition, the present embodiment also provides a method for manufacturing the capacitive pressure sensor, which mainly comprises laminating and bonding the first electrode layer 1, the dielectric layer 2, the insulating layer 4 and the second electrode layer 3 together in sequence. The first electrode layer 1, the dielectric layer 2, the insulating layer 4 and the second electrode layer 3 can be formed by directly adopting formed functional layers, or can be formed into corresponding functional layers in the preparation process. For example, the insulating layer 4 may be an insulating film directly, or may be formed by spin-coating an insulating layer glue solution on other layers by spraying, spin-coating, or the like, or by forming an insulating target by a magnetron sputtering process during the preparation process.

Specifically, the preparation method is to form a first electrode layer 1 and a second electrode layer 3, and form an insulating layer 4 on the second electrode layer 3; one side of the dielectric layer 2 is attached to the first electrode layer 1, and one side of the dielectric layer 2 facing away from the first electrode layer 1 is laminated and combined with one side of the insulating layer 4 facing away from the second electrode layer 3. A buffer layer 9 may be further provided, where the buffer layer 9 is disposed in the circumferential direction of the dielectric layer 2; the buffer layer 9 is pressed or glued between any combination of layers of the dielectric layer 2 on the side close to the first electrode layer 1 and layers of the dielectric layer 2 on the side facing away from the first electrode layer 1. The first electrode layer 1 is typically bonded to one side of the dielectric layer 2 with a conductive adhesive, the insulating layer 4 is bonded to the other side of the dielectric layer 2, and all layers are pressed together.

As an implementation method, the specific preparation process is as follows:

(1) Manufacturing a first electrode layer 1:

s1, providing a cleaned first insulating film 5 as a substrate film;

s2, preparing an electrode layer metal material, and forming the first electrode layer 1 on the first insulating film 5 through silk-screen printing (silk-screen printing metal slurry and curing) or magnetron sputtering, wherein conductive circuits can be connected to the outside in a printing mode such as silk-screen printing or sputtering at the same time so as to be convenient for connecting an external circuit.

(2) Manufacturing a second electrode layer 3 and an insulating layer 4:

s3, the preparation method of the second electrode layer 3 is the same as the preparation method of the first electrode layer 1, after the second electrode layer 3 is formed on the second insulating film 7, an insulating layer glue solution is prepared, and the prepared insulating layer glue solution is coated or sputtered on the first electrode layer 1 or the second electrode layer 3 through a spraying, coating or magnetron sputtering process, so that the insulating layer glue solution completely covers the first electrode layer 1 or the second electrode layer 3, and the insulating layer 4 is formed. In this embodiment, the insulating layer glue solution is a mixed solution of n-hexane and silicon-containing adhesive glue, and after spin coating, the insulating layer is cured, and the spin-coated insulating layer 4 can be made very thin by adopting the composition, which is beneficial to capacitance performance.

(3) And (3) packaging:

s4, preparing a dielectric layer 2, surrounding the dielectric layer 2 and also surrounding a buffer layer 9, bonding contact interfaces among the first electrode layer 1, the dielectric layer 2 and the insulating layer 4 which are sequentially laminated by adopting conductive adhesive, and bonding and connecting the mounting interfaces of the buffer layer 9 in the sensor by adopting adhesive, so that the capacitive pressure sensor is obtained by pressing. The conductive adhesive is adopted for bonding, so that the interface bonding is better, and the colloid is not used as a dielectric substance to participate in the calculation of the capacitance value.

Second embodiment

Referring to fig. 3 and 4, the present embodiment provides a capacitive pressure sensor, which has substantially the same structure as the first embodiment, except that: the structure of the embodiment comprises a first electrode layer 1, a dielectric layer 2, an insulating layer 4 and a second electrode layer 3 which are sequentially stacked from top to bottom, wherein the first electrode layer 1 and the second electrode layer 3 are flexible conductive colloid layers, the glue adopted in the flexible conductive colloid layers and the glue adopted in the conductive adhesive glue are the same type of materials, the insulating layer 4 is insulating silica gel, and a buffer layer 9 is also arranged around the dielectric layer 2; after encapsulation, a first encapsulation film 6 is arranged on one side of the first electrode layer 1, which is away from the dielectric layer 2, a second encapsulation film 14 is arranged on one side of the second electrode layer 3, which is away from the dielectric layer 2 or the insulating layer 4, and the capacitive pressure sensor is encapsulated by using the first encapsulation film 6 and the second encapsulation film 14, wherein the materials of the encapsulation films can be PU, PET, PI, and the first encapsulation film 6 and the second encapsulation film 14 in the embodiment are PU films with the thickness of 100 μm.

The preparation method of the capacitive pressure sensor comprises the following steps:

(1) Manufacturing a first electrode layer 1 and a second electrode layer 3:

p1, preparing a conductive material, silica gel base glue, a coupling agent and a catalyst, wherein the mass ratio of the conductive filler is 2% -15%; preparing a solvent, and preparing a silica gel base gel, a coupling agent, a catalyst and the solvent according to the mass ratio of 30-75:8-13:1:200-300, stirring and mixing the components to obtain a mixture I; specifically, the first mixture comprises the following components: PDMS base adhesive, tetraethoxysilane (TEOS), dibutyl tin dilaurate (DBTDL) and conductive materials, wherein the solvent can be chloroform, butyl acetate, cyclohexanone, isopropanol and the like, and the mass ratio of the PDMS base adhesive to the tetraethoxysilane to the dibutyl tin dilaurate to the butyl acetate is 50:10:1:250.

p2, carrying out ultrasonic treatment on the mixture I obtained in the step P1 in a low-temperature environment (ice water bath);

and P3, pouring the mixture obtained in the step P2 into a mould, standing and solidifying to obtain the flexible conductive colloid layers serving as the first electrode layer 1 and the second electrode layer 3 respectively.

In other embodiments, after step P2, further comprising step P2': preparing a metal sheet or a conductive film, and preparing a hollowed-out structure through shearing, punching, laser imprinting or chemical etching; and (3) completely coating the hollow structure with the mixture obtained in the step (P2). And P3, standing and solidifying the coating structure obtained in the step P2', namely respectively obtaining flexible conductive colloid layers serving as the first electrode layer 1 and the second electrode layer 3, thereby ensuring that the flexible conductive colloid layers serving as the electrode layers can be electrically connected with an external circuit stably.

(2) And (3) packaging:

p4, preparing a swelling solution: the same silica gel base gel, coupling agent, catalyst and solvent as in the step P1 are mixed according to the mass ratio of 30-75:8-13:1:400-500, and performing ultrasonic treatment for 10-60 min to obtain uniformly dispersed non-conductive glue solution as swelling solution; specifically, the components of the swelling solution are: the mass ratio of PDMS base adhesive to tetraethyl orthosilicate (TEOS) to dibutyl tin dilaurate (DBTDL) to butyl acetate is 50:10:1:450, sonicating for 40min.

P5, soaking each adhesive layer of the first electrode layer 1, the second electrode layer 3 and the dielectric layer 2 in the swelling solution in the step P4 for at least 3 hours for swelling treatment;

p6, taking out the first electrode layer 1, the second electrode layer 3 and the dielectric layer 2 which are soaked in the step P5 from the swelling solution, and volatilizing the solvent at room temperature;

and P7, after the first electrode layer 1, the dielectric layer 2, the insulating layer 4 and the second electrode layer 3 obtained in the step P6 are sequentially stacked, placing the layers for 1-5 hours under the pressure of 20-500kPa, at normal temperature or in an environment with the temperature raised to 120 ℃, specifically, placing the layers for 2 hours under the pressure of 100kPa, and in the environment with the temperature raised to 70 ℃, and bonding the interfaces of the layers together in a chemical bonding mode, thus obtaining the sensor finished product.

In other embodiments, the insulating layer 4 may be an insulating film material or a flexible insulating material, and the insulating layer 4 may be placed in a swelling solution for swelling treatment.

Third embodiment

Referring to fig. 5 and 6, the present embodiment provides a capacitive pressure sensor, which has substantially the same structure as the first embodiment, except that: the structure of the embodiment comprises a first insulating film 5, a first electrode layer 1, a dielectric layer 2, an insulating layer 4 and a second electrode layer 3 which are sequentially stacked from top to bottom, wherein the first electrode layer 1 is a metal layer, the second electrode layer 3 is a flexible conductive colloid layer, and a buffer layer 9 is also arranged around the dielectric layer 2; after packaging, a second packaging film 14 is arranged under the second electrode layer 3, and the capacitive pressure sensor is packaged by using the first insulating film 5 and the second packaging film 14. The first electrode layer 1 is fabricated in the manner described in the first embodiment, and the second electrode layer 3 is fabricated in the manner described in the second embodiment.

Fourth embodiment

Referring to fig. 7 and 8, the present embodiment provides an array sensor, which includes a plurality of sensing units, the sensing units are substantially the same as the capacitive pressure sensor structure of the first embodiment, except that the buffer layer 9 of the sensing units only surrounds the first electrode layer 1 and the dielectric layer 2 correspondingly, all the sensing units are horizontally arranged and dispersedly arranged, are generally arranged in an array, are packaged up and down by adopting the first insulating film 5 and the second insulating film 7, are connected between electrode layers with the same polarity in all the capacitive pressure sensors through wires or flexible circuits, and are finally led out to an external connection terminal for connection with an external control circuit, specifically, all the first electrode layers 1 are connected together through the first wires 8 and are finally led out to the external first connection terminal 11, and all the second electrode layers 3 are connected together through the second wires 10 and are finally led out to the external second connection terminal 12. In this embodiment, the first insulating film 5 and the second insulating film 7 as the packaging layers are used for carrying and packaging each sensing unit, and all the sensing units share the first insulating film 5, the second insulating film 7 and the insulating layer 4, so that each capacitive pressure sensor can be ensured to work independently, and the formed array sensor has strong integrity; the first insulating film 5, the second insulating film 7, the insulating layer 4 and the buffer layer 9 are further provided with through holes 13, and the through holes 13 generally penetrate through the upper and lower packaging structures to enable good fit.

The preparation method of the array sensor in this embodiment refers to the preparation method in the first embodiment, and is not described herein.

Fifth embodiment

Referring to fig. 9, the present embodiment provides an array sensor, which includes a plurality of sensing units, the sensing units are substantially the same as the capacitive pressure sensor structure of the second embodiment, and the difference is that the buffer layer 9 of the sensing unit only correspondingly surrounds the periphery of the first electrode layer 1 and the dielectric layer 2, all the sensing units are horizontally laid and distributed, are generally arranged in an array, and are vertically packaged by adopting the first packaging film 6 and the second packaging film 14, and the electrode layers with the same polarity in all the capacitive pressure sensors are connected through wires or flexible circuits and finally led out to an external wiring terminal. In this embodiment, the first packaging film 6 and the second packaging film 14 as packaging layers are used for packaging each sensing unit, and all the sensing units share the insulating layer 4; the first packaging film 6, the second packaging film 14, the insulating layer 4 and the buffer layer 9 are further provided with through holes 13, and the through holes 13 generally penetrate through the upper and lower packaging structures.

The preparation method of the array sensor in this embodiment refers to the preparation method in the second embodiment, and is not described herein. The obtained sensor unit or the upper and lower packaging layers of the array sensor can be packaged by adopting a conventional packaging process (such as double-sided adhesive tape and pressure-sensitive adhesive bonding a layer of packaging film) to respectively form the packaging layers.

Sixth embodiment

Referring to fig. 10, the present embodiment provides an array sensor, which includes a plurality of sensing units, the sensing units are substantially the same as the capacitive pressure sensor structure of the second embodiment, and the difference is that the buffer layer 9 of the sensing unit only correspondingly surrounds the periphery of the first electrode layer 1 and the dielectric layer 2, all the sensing units are horizontally laid and distributed, are generally arranged in an array, are vertically packaged by adopting the first insulating film 5 and the second packaging film 14, are connected through wires or flexible circuits, and are finally led out to an external wiring terminal. In this embodiment, the first insulating film 5 is used for carrying and packaging each sensing unit, the second packaging film 14 is used for packaging each sensing unit, and all sensing units share the first insulating film 5 and the insulating layer 4; the first insulating film 5, the second packaging film 14, the insulating layer 4 and the buffer layer 9 are further provided with through holes 13, and the through holes 13 generally penetrate through the upper and lower packaging structures.

The preparation method of the array sensor in this embodiment refers to the preparation method in the third embodiment, and is not described herein.

Seventh embodiment

The present embodiment provides a capacitive pressure sensor, which is different from the first embodiment in that: the dielectric layer is void free.

First comparative example

The present comparative example provides a capacitive pressure sensor, which is different from the first embodiment in that: in this embodiment, an insulating layer is added between the first electrode layer and the dielectric layer, so that both sides of the dielectric layer have the same insulating layer.

Second comparative example

The present comparative example provides a capacitive pressure sensor, which is different from the first embodiment in that: the dielectric layer is free of non-metallic conductive filler.

Third comparative example

The present comparative example provides a capacitive pressure sensor, which is different from the first embodiment in that: the dielectric layer is void free and free of non-metallic conductive filler.

Fourth comparative example

The present comparative example provides a capacitive pressure sensor, which is different from the first embodiment in that: the comparative example was not provided with an insulating layer.

Performance test:

the test equipment comprises an LCR test instrument (model: KEYSIGHT E4980EA, fitting 16334A) and a pressure measurement instrument (model: su Ce SH-100N), wherein auxiliary materials are a test platform and a wire.

The test mode is as follows: placing a sensor to be tested on a test platform, and connecting a first electrode and a second electrode of the sensor to an LCR tester through crocodile clip wires respectively for reading capacitance values (output values, unit pF, coordinate Y axis); the probe applies sensor pressure through a descending pressure testing instrument, and the pressure (input value, unit N) of the pressure measuring instrument is read; according to the area and the pressure of the probe, calculating the pressure value (unit kPa) of the sensor to determine an X-axis coordinate, and reading the capacitance value (unit pF) of the LCR tester to determine a Y-axis coordinate; and fitting according to the values of the X and Y axes of the tested point positions to obtain a pressure response curve of the sensor.

1. The performance of the capacitive pressure sensor of the first embodiment was tested, the pressure response curve of which is shown in fig. 11, and the performance parameters of which are shown in table 1.

Table 1 performance parameter table of capacitive pressure sensor

As can be seen from fig. 11 and table 1, the capacitive pressure sensor of the present embodiment has the characteristics of large sensitivity response range, wide pressure bearing value range, high sensitivity, and fast sensor response speed.

2. The pressure response of the first, seventh, second, and third comparative examples was tested and the results are shown in fig. 12, wherein the pressure response lines of the first, seventh, second, and third comparative examples were a, b, c, d, respectively.

As can be seen from fig. 12, the dielectric layer of the present embodiment can ensure a large pressure response range of the sensor, and has high sensitivity, while the dielectric layer of the third comparative example is non-conductive and non-porous, and has relatively poor sensitivity, and compared with the dielectric layer of the third comparative example, the dielectric layer of the first embodiment is conductive and porous, and the sensitivity improvement is very obvious, and the dielectric layer of the seventh embodiment is conductive and non-porous, and the sensitivity is improved to a certain extent.

3. The pressure response of the first example, the first comparative example and the fourth comparative example were tested, and the pressure response lines of the first example, the first comparative example and the fourth comparative example are b, c and a, respectively, as shown in fig. 13.

As can be seen from fig. 13, the arrangement of the dielectric layer and the insulating layer on one side of the dielectric layer in this embodiment can ensure the high sensitivity of the sensor, while the arrangement of the dielectric layer and the insulating layers on both sides of the dielectric layer is less.

In summary, the capacitive pressure sensor and the array sensor in the embodiments of the present application have high sensitivity, wide pressure bearing value range and strong stability.

The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. The capacitive pressure sensor is characterized by comprising a first electrode layer, a dielectric layer and a second electrode layer which are sequentially stacked, wherein the dielectric layer contains conductive filler, the conductive filler comprises at least one of nonmetal conductive filler, conductive oxide filler and semiconductor filler, and an insulating layer is further arranged between the first electrode layer or the second electrode layer and the dielectric layer.

2. The capacitive pressure sensor of claim 1, wherein the dielectric layer has a porosity of 30% -99%.

3. The capacitive pressure sensor of claim 1, wherein the dielectric layer comprises an elastomeric layer and the conductive filler is dispersed in the elastomeric layer.

4. The capacitive pressure sensor of claim 3, wherein the non-metallic conductive filler is selected from at least one of carbon nanotubes, graphene, carbon powder, PEDOT polymer, polyaniline, polythiophene, polystyrene sulfonate, and polycarbazole; the conductive oxide filler is at least one selected from copper oxide, iron oxide, tin oxide, tungsten oxide and manganese oxide; the semiconductor filler is selected from at least one of silicon, germanium, cadmium selenide, gallium arsenide, germanium arsenide, and gallium nitride.

5. The capacitive pressure sensor of claim 1, wherein the dielectric layer has a thickness of 0.1mm-10mm.

6. The capacitive pressure sensor of claim 1, wherein the insulating layer is at least one of PMMA, PI, PE, PET, PPS, PU, FEP, PFA, ETFE, PEEK, polysilazane, alumina, quartz, an organic polymer, polycarbonate, silicone, a fluoride material, rubber, ceramic, a high molecular polymer, and silica.

7. The capacitive pressure sensor of claim 1, wherein the insulating layer has a thickness of 10nm-50 μm.

8. The capacitive pressure sensor of claim 1, further comprising a buffer layer surrounding the dielectric layer, the buffer layer being an insulating material, the thickness range of the dielectric layer being within the thickness range of the buffer layer;

optionally, the elastic modulus of the buffer layer is not less than the elastic modulus of the dielectric layer;

9. The capacitive pressure sensor of claim 1, wherein the first electrode layer is a metallic or non-metallic conductive material and the second electrode layer is a metallic or non-metallic conductive material;

10. The capacitive pressure sensor of claim 1, wherein the first electrode layer has a thickness of 20nm-2000 μm and the second electrode layer has a thickness of 20nm-2000 μm.

11. An array sensor, characterized in that it comprises a plurality of capacitive pressure sensors according to any one of claims 1 to 10, all of which are laid flat and distributed, and all of which are connected by a circuit between electrode layers of the same polarity and led out to the outside.

12. The array sensor of claim 11, wherein all of the capacitive pressure sensors are encapsulated by an encapsulation layer, and wherein through holes are formed around the dielectric layer.

13. A method of manufacturing a capacitive pressure sensor according to any one of claims 1 to 10, characterized in that the first electrode layer, the dielectric layer, the insulating layer and the second electrode layer are laminated and bonded together in this order.

14. The method of manufacturing a capacitive pressure sensor according to claim 13, wherein,

forming the first electrode layer and the second electrode layer, and forming an insulating layer on the second electrode layer; and attaching one side of the dielectric layer to the first electrode layer, and laminating and combining one side of the dielectric layer, which is away from the first electrode layer, with one side of the insulating layer, which is away from the second electrode layer.

15. The method of manufacturing a capacitive pressure sensor according to claim 14, wherein,

providing a buffer layer, wherein the buffer layer is arranged on the circumference of the dielectric layer; the buffer layer is pressed or adhered between any combination of layers on one side of the dielectric layer close to the first electrode layer and layers on one side of the dielectric layer away from the first electrode layer.

16. The method of manufacturing a capacitive pressure sensor according to claim 15, wherein,

and bonding the first electrode layer on one side of the dielectric layer by adopting conductive bonding adhesive, bonding the insulating layer on the other side of the dielectric layer, and pressing all the layers together.

17. The method of manufacturing a capacitive pressure sensor according to claim 13, wherein the first electrode layer, the second electrode layer, and the dielectric layer in the capacitive pressure sensor are all resin polymer layers, comprising the steps of:

and stacking the first electrode layer, the dielectric layer, the insulating layer and the second electrode layer after swelling treatment, and pressing to bond the layers together.