Pressure sensor, pressure sensing array and preparation method thereof

Abstract

The invention relates to a pressure sensor, a pressure sensing array and a preparation method thereof. The pressure sensor includes: a first substrate; the first sensing electrode is positioned on the upper surface of the first substrate; the first insulating layer is located on the surface of the first sensing electrode and comprises a plurality of first microspheres arranged in an array or is a first hollow film layer; the first pressure-sensitive layer is positioned on the surface of the first insulating layer and is filled in a first gap in the first insulating layer; a second substrate over the first substrate; the second sensing electrode is positioned on the lower surface of the second substrate; the second insulating layer is located on the surface of the second sensing electrode, and the second insulating layer comprises a plurality of second microspheres arranged in an array or a second hollow film layer; and the second pressure-sensitive layer is located on the surface of the second insulating layer, and the second gap in the second insulating layer is filled with the second pressure-sensitive layer. The pressure sensor provided by the invention has higher sensitivity under high pressure and thin thickness.

Description

Technical Field

[0001] The present invention relates to the field of sensing technology, and in particular to a pressure sensor, a pressure sensing array and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of wearable products, flexible sensor components have become one of the hot topics explored by researchers. Among them, flexible pressure sensors have received particular attention and have very broad market prospects in the fields of artificial electronic skin, flexible touch screens, intelligent robots, and medical health.

[0003] At present, the research on flexible pressure sensors can be based on a variety of working principles, mainly including: capacitive, resistive, piezoelectric and thin film transistor. Among them, resistive pressure sensors are widely used due to their simple structure and lack of external electromagnetic interference. However, after the thickness of the sensitive film of the resistive pressure sensor is reduced, there is a problem of decreased sensitivity due to the increase in the sensing range.

[0004] Therefore, how to reduce the thickness of the resistive pressure sensor while improving the sensitivity and sensing range of the resistive pressure sensor is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides a pressure sensor, a pressure sensing array and a preparation method thereof, which are used to solve the problem that the current ultra-thin pressure sensor cannot have both high sensitivity and a large sensing range, so as to improve the performance of the pressure sensor and expand the application field of the pressure sensor.

[0006] According to some embodiments, the present invention provides a pressure sensor, comprising:

[0007] A first substrate, comprising an upper surface and a lower surface that are oppositely distributed;

[0008] A first sensing electrode, located on the upper surface of the first substrate;

[0009] A first insulating layer is located on a surface of the first sensing electrode facing away from the first substrate, the first insulating layer includes a plurality of first microspheres arranged in an array or the first insulating layer is a first hollow film layer having a first hollow structure;

[0010] A first piezoresistive layer is located on a surface of the first insulating layer facing away from the first substrate, the first piezoresistive layer is also filled in a first gap in the first insulating layer and is in contact with and connected to the first sensing electrode, the first gap is located between adjacent first microspheres or the first gap is the first hollow structure, and the first piezoresistive layer is a first piezoresistive film layer having a first microstructure on a surface facing away from the first substrate;

[0011] a second substrate, located above the first substrate, the second substrate comprising an upper surface and a lower surface that are oppositely distributed, and the lower surface of the second substrate is arranged toward the upper surface of the first substrate;

[0012] A second sensing electrode is located on the lower surface of the second substrate;

[0013] A second insulating layer is located on a surface of the second sensing electrode facing away from the second substrate, the second insulating layer includes a plurality of second microspheres arranged in an array or the second insulating layer is a second hollow film layer having a second hollow structure;

[0014] The second piezoresistive layer is located on the surface of the second insulating layer facing away from the second substrate. The second piezoresistive layer also fills the second gap in the second insulating layer and is in contact with the second sensing electrode. The second gap is located between adjacent second microspheres or the second gap is the second hollow structure. The second piezoresistive layer is a second piezoresistive film layer having a second microstructure on the surface facing away from the second substrate.

[0015] In some embodiments, the material of the first piezoresistive film layer and the material of the second piezoresistive film layer are both polymers doped with conductive nanomaterials, the doping concentration of the conductive nanomaterials in the polymers is in the percolation region, and the doping concentration is 0.5% to 10%.

[0016] In some embodiments, the plurality of the first microspheres in the first insulating layer are arranged in a single-layer array, and the plurality of the second microspheres in the second insulating layer are also arranged in a single-layer array;

[0017] The first microspheres in the first insulating layer have the same size or the first insulating layer includes the first microspheres of two sizes;

[0018] The sizes of the plurality of second microspheres in the second insulating layer are the same or the second insulating layer includes two second microspheres of different sizes;

[0019] The size of the first microsphere and the diameter of the second microsphere are both 0.1 micrometer to 10 micrometers.

[0020] In some embodiments, the material of the first microsphere and the material of the second microsphere are the same, and are both epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silicon dioxide.

[0021] In some embodiments, the shape of the first hollow structure is the same as the shape of the second hollow structure, both of which are circular or square;

[0022] The distance between adjacent first hollow structures in the first insulating layer is 10 micrometers to 100 micrometers, and the distance between adjacent second hollow structures in the second insulating layer is 10 micrometers to 100 micrometers.

[0023] In some embodiments, the material of the first sensing electrode and the material of the second sensing electrode are any one of a conductive polymer, a carbon-based conductor, a metal oxide, a metal nanowire, a metal and metal oxide nanoparticles, and a conductive paste based on carbon-based conductors, metal nanowires, metal and metal oxide nanoparticles.

[0024] According to some other embodiments, the present invention further provides a pressure sensing array, comprising:

[0025] A plurality of pressure sensors as described above, wherein the plurality of pressure sensors are arranged in an array;

[0026] The first sensing electrodes in the plurality of pressure sensors arranged in the same row are electrically connected and collectively serve as row electrodes;

[0027] The second sensing electrodes in the plurality of pressure sensors arranged in the same column are electrically connected and collectively serve as column electrodes, and the column electrodes are arranged orthogonally to the row electrodes;

[0028] The pressure sensing array also includes an adhesive layer, which is sandwiched between the first insulating layer and the second insulating layer. The adhesive layer has a plurality of openings corresponding to the plurality of pressure sensors. The first pressure-sensitive layer and the second pressure-sensitive layer in each of the pressure sensors are located in the corresponding openings, and the position of each of the openings is aligned with the first sensing electrode and the second sensing electrode in one of the pressure sensors.

[0029] In some embodiments, the Young's modulus of the first pressure-sensitive layer is equal to the Young's modulus of the second pressure-sensitive layer, and the Young's modulus of the adhesive layer is less than or equal to the Young's modulus of the first pressure-sensitive layer;

[0030] The thickness of the adhesive layer is equal to the sum of the thicknesses of the first pressure-sensitive layer and the second pressure-sensitive layer.

[0031] According to some further embodiments, the present invention further provides a method for preparing the pressure sensing array as described above, comprising the following steps:

[0032] providing a first substrate and a second substrate;

[0033] forming the row electrodes on the upper surface of the first substrate, and forming the column electrodes on the lower surface of the second substrate;

[0034] forming a first insulating layer covering the row electrodes, and forming a second insulating layer covering the column electrodes;

[0035] Forming a first pressure-sensitive layer on a surface of the first insulating layer facing away from the first substrate, and forming a second pressure-sensitive layer on a surface of the second insulating layer facing away from the second substrate, wherein the first pressure-sensitive layer is aligned with the second pressure-sensitive layer, and the size of the first pressure-sensitive layer is equal to the size of the second pressure-sensitive layer;

[0036] forming the adhesive layer on the surface of the first insulating layer facing away from the first substrate, wherein the adhesive layer has a plurality of openings exposing the first pressure-sensitive layer;

[0037] The second insulating layer is laminated on the adhesive layer along the direction in which the second pressure-sensitive layer is aligned with the first pressure-sensitive layer, so that the row electrodes and the column electrodes are arranged orthogonally.

[0038] In some embodiments, the first pressure-sensitive layer is prepared by screen printing, doctor blade coating or spray coating;

[0039] The adhesive layer forms the opening by laser cutting a double-sided adhesive film, and the adhesive layer with the opening is transferred to the surface of the first insulating layer; or, the adhesive layer with the opening is directly formed on the surface of the first insulating layer by dispensing, screen printing, scraping or spraying.

[0040] The pressure sensor, pressure sensing array and preparation method provided by the present invention are as follows: by arranging closely arranged first microspheres or a first hollow film layer with a first hollow structure on the surface of the first sensing electrode, and arranging closely arranged second microspheres or a second hollow film layer with a second hollow structure on the surface of the second sensing electrode, a microstructure is formed on the surface of the first pressure-sensitive layer and the second pressure-sensitive layer covering the surface, so that the interface contact resistance between the two sensitive layers (i.e., the first pressure-sensitive layer and the second pressure-sensitive layer) is reduced due to the increase of the contact area when the first pressure-sensitive layer or the second pressure-sensitive layer is subjected to force, thereby simultaneously achieving the effect of increasing the resistance of the sensor and reducing the power consumption of the sensor by reducing the contact area between the interface of the sensitive layer and between the sensitive layer and the electrode layer. At the same time, by adjusting the concentration of the conductive nanomaterial in the first pressure-sensitive layer and the second pressure-sensitive layer to the percolation zone, the slight thickness change of the first pressure-sensitive layer and the second pressure-sensitive layer when subjected to pressure can cause the reduction of the internal resistance of the film, thereby improving the sensitivity of the pressure sensor. In addition, the present invention increases the range of the pressure sensor by changing the contact area of ​​the microstructure between the first pressure-sensitive layer and the second pressure-sensitive layer of high modulus. The pressure sensing array provided by the present invention has an adhesive layer, which can improve the electrical stability of the pressure sensing array under high pressure and lateral shear force. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic cross-sectional view of a pressure sensor in a specific embodiment of the present invention;

[0042] Figure 2 is a flow chart of a method for preparing a pressure sensing array in a specific embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of the structure after row electrodes are formed in a specific embodiment of the present invention;

[0044] Figure 4 is a schematic diagram of a structure after a first insulating layer is formed in a specific embodiment of the present invention;

[0045] Figure 5 is a schematic diagram of the structure after the first pressure-sensitive layer is formed in a specific embodiment of the present invention;

[0046] Figure 6 is a schematic diagram of the structure after forming an adhesive layer in a specific embodiment of the present invention;

[0047] Figure 7 It is a schematic diagram of the structure after the second pressure-sensitive layer is attached to the adhesive layer in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0048] The specific implementation methods of the pressure sensor, pressure sensing array and preparation method thereof provided by the present invention are described in detail below with reference to the accompanying drawings.

[0049] This specific embodiment provides a pressure sensor, Figure 1 FIG. 1 is a schematic cross-sectional view of a pressure sensor in a specific embodiment of the present invention. Figure 1 As shown, the pressure sensor comprises:

[0050] The first substrate 100 includes an upper surface and a lower surface that are oppositely distributed;

[0051] A first sensing electrode 101 is located on the upper surface of the first substrate 100;

[0052] A first insulating layer 102 is located on a surface of the first sensing electrode 101 facing away from the first substrate 100 , wherein the first insulating layer 102 includes a plurality of first microspheres arranged in an array or the first insulating layer 102 is a first hollow film layer having a first hollow structure;

[0053] A first piezoresistive layer 103 is located on a surface of the first insulating layer 102 facing away from the first substrate 100. The first piezoresistive layer 103 is also filled in a first gap in the first insulating layer 102 and is in contact with the first sensing electrode 101. The first gap is located between adjacent first microspheres or the first gap is the first hollow structure. The first piezoresistive layer 103 is a first piezoresistive film layer having a first microstructure on a surface facing away from the first substrate 100.

[0054] A second substrate 200 is located above the first substrate 100, the second substrate 200 includes an upper surface and a lower surface that are relatively distributed, and the lower surface of the second substrate 200 is arranged toward the upper surface of the first substrate 100;

[0055] A second sensing electrode 201 is located on the lower surface of the second substrate 200;

[0056] A second insulating layer 202 is located on a surface of the second sensing electrode 201 facing away from the second substrate 200, wherein the second insulating layer 202 includes a plurality of second microspheres arranged in an array or the second insulating layer is a second hollow film layer having a second hollow structure;

[0057] The second piezoresistive layer 203 is located on the surface of the second insulating layer 202 facing away from the second substrate 200. The second piezoresistive layer 203 is also filled in the second gap in the second insulating layer 202 and is in contact with the second sensing electrode 201. The second gap is located between adjacent second microspheres or the second gap is the second hollow structure. The second piezoresistive layer 203 is a second piezoresistive film layer having a second microstructure on the surface facing away from the second substrate 200.

[0058] Specifically, if Figure 1As shown, the first substrate 100 includes an upper surface and a lower surface that are oppositely distributed, and the second substrate 200 also includes an upper surface and a lower surface that are oppositely distributed. The second substrate 200 is located above the first substrate 100, and the lower surface of the second substrate 200 is opposite to the upper surface of the first substrate 100. The first sensing electrode 101, the first insulating layer 102, and the first pressure-sensitive layer 103 are sequentially stacked on the upper surface of the first substrate 100 along a direction perpendicular to the upper surface of the first substrate 100. The second sensing electrode 201, the second insulating layer 202, and the second pressure-sensitive layer 203 are sequentially stacked on the lower surface of the second substrate 200 along a direction perpendicular to the lower surface of the second substrate 200. The upper surface of the first substrate 100 is parallel to the lower surface of the second substrate 200. The first insulating layer 102 includes a plurality of first microspheres arranged in an array or the first insulating layer 102 is a first hollow film layer with a first hollow structure, so that there are gaps in the first insulating layer 102, namely the first gaps, and the surface of the first insulating layer 102 away from the first substrate 100 is a rough surface with a regular structure. Since part of the first pressure-sensitive layer 103 is filled in the first gaps, the surface of the first pressure-sensitive layer 103 away from the first substrate 100 is uneven, that is, the first microstructure is formed on the surface of the first pressure-sensitive layer 103 away from the first substrate 100. The second insulating layer 202 includes a plurality of second microspheres arranged in an array or the second insulating layer 202 is a second hollow film layer with a second hollow structure, so that there are gaps in the second insulating layer 202, namely the second gaps, and the surface of the second insulating layer 202 away from the second substrate 200 is a rough surface with a regular structure. Since part of the second pressure-sensitive layer 103 is filled in the second gap, the surface of the second pressure-sensitive layer 203 facing away from the second substrate 200 is uneven, that is, the second microstructure is formed on the surface of the second pressure-sensitive layer 203 facing away from the second substrate 200. In one example, the thickness of the first pressure-sensitive layer 103 and the thickness of the second pressure-sensitive layer 203 are both 15 micrometers to 100 micrometers.

[0059] Due to the presence of the first microstructure and the second microstructure, when the pressure sensor receives external pressure, the contact area between the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 will change, so that the interface contact resistance between the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 will also change accordingly, thereby simultaneously achieving the effect of increasing the resistance of the pressure sensor and reducing the power consumption of the sensor by reducing the contact area between the sensitive layer interfaces (i.e., the contact interface between the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203) and the contact area between the sensitive layer and the electrode layer (i.e., the contact area between the first pressure-sensitive layer 103 and the first sensing electrode 101 and the contact area between the second pressure-sensitive layer 203 and the second sensing electrode 201). The pressure sensor provided in this specific embodiment is not limited by the thickness of the first pressure-sensitive layer 103 and the thickness of the second pressure-sensitive layer 203, and can therefore have both high sensitivity and a large sensing range, thereby improving the performance of the pressure sensor.

[0060] In one example, the first substrate 100 and the second substrate 200 are both used as the carrier substrate of the pressure sensor, wherein the material of the first substrate 100 and the material of the second substrate 200 can be polyurethane, polyimide, polyethylene terephthalate plastic, polyethylene naphthalate, polydimethylsiloxane, polyurethane or platinum-catalyzed silica gel.

[0061] In some embodiments, the material of the first piezoresistive film layer and the material of the second piezoresistive film layer are both polymers doped with conductive nanomaterials, the doping concentration of the conductive nanomaterials in the polymers is in the percolation region, and the doping concentration is 0.5% to 10%.

[0062] For example, the conductive nanomaterial is nano-carbon powder, nano-graphite, carbon nanotube or nano-graphene, and the polymer material is polyimide, polyvinylidene fluoride, polyurethane or polydimethylsiloxane. In the pressure sensor provided in this specific embodiment, the doping concentration of the conductive nanomaterial in the polymer in the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 is located in the percolation zone, and the spacing of the conductive nanomaterials decreases under the action of external pressure, causing the conductivity to increase. At the same time, the microstructures on the surfaces of the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 are arranged relative to each other, and the area of ​​the microstructure interface increases under the action of external pressure, thereby improving the sensitivity of the pressure sensor.

[0063] In some embodiments, the plurality of first microspheres in the first insulating layer 102 are arranged in a single-layer array, and the plurality of second microspheres in the second insulating layer 202 are also arranged in a single-layer array;

[0064] The first microspheres in the first insulating layer 102 have the same size or the first insulating layer 102 includes the first microspheres of two sizes;

[0065] The sizes of the plurality of second microspheres in the second insulating layer 202 are the same or the second insulating layer 202 includes second microspheres of two different sizes;

[0066] The size of the first microsphere and the diameter of the second microsphere are both 0.1 micrometer to 10 micrometers.

[0067] Specifically, the first insulating layer 102 and the second insulating layer 202 are both tightly arranged single-layer microspheres or hollow films formed by photolithography, and there are gaps between the tightly arranged microspheres and there are hollow structures in the hollow films. The gaps between the tightly arranged microspheres and the hollow structures in the hollow films make the first insulating layer 102 and the second insulating layer 202 have rough surfaces, and the rough surfaces are rough surfaces with regular structures. The gaps between the tightly arranged microspheres and the hollow structures in the hollow films also provide a connection channel for the pressure-sensitive layer (for example, the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203) and the sensing electrode (for example, the first sensing electrode 101 and the second sensing electrode 201). In one example, the plurality of the first microspheres in the first insulating layer 102 are solid microspheres of a single or double size, and the plurality of the second microspheres in the second insulating layer 202 are also solid microspheres of a single or double size. In another example, the arrangement and size of the first microspheres in the first insulating layer 102 are the same as the arrangement and size of the second microspheres in the second insulating layer 202 .

[0068] In some embodiments, the material of the first microsphere and the material of the second microsphere are the same, and are both epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silicon dioxide.

[0069] In some embodiments, the shape of the first hollow structure is the same as the shape of the second hollow structure, both of which are circular or square;

[0070] The distance between adjacent first hollow structures in the first insulating layer 102 is 10 micrometers to 100 micrometers, and the distance between adjacent second hollow structures in the second insulating layer 202 is 10 micrometers to 100 micrometers.

[0071] In some embodiments, the material of the first sensing electrode 101 and the material of the second sensing electrode 201 are any one of conductive polymers, carbon-based conductors, metal oxides, metal nanowires, metal and metal oxide nanoparticles, and conductive pastes based on carbon-based conductors, metal nanowires, metal and metal oxide nanoparticles.

[0072] For example, the conductive polymer is poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), polystyrene sulfonic acid, polyaniline, polythiophene or polypyrrole having an acidic or neutral pH value. The carbon-based conductive material is single-layer or multi-layer graphene, graphite, carbon black, single-wall or multi-wall carbon nanotube. The metal is gold, silver, copper, aluminum or nickel. The metal oxide is indium tin oxide or fluorine-doped tin oxide.

[0073] In addition, this specific embodiment also provides a pressure sensing array, including:

[0074] A plurality of pressure sensors as described above (see Figure 1 ), and a plurality of the pressure sensors are arranged in an array;

[0075] The first sensing electrodes 101 in the plurality of pressure sensors arranged in the same row are electrically connected and collectively serve as row electrodes;

[0076] The second sensing electrodes 201 in the plurality of pressure sensors arranged in the same column are electrically connected and collectively serve as column electrodes, and the column electrodes are arranged orthogonally to the row electrodes;

[0077] The pressure sensing array also includes an adhesive layer, which is sandwiched between the first insulating layer 102 and the second insulating layer 202. The adhesive layer has a plurality of openings corresponding to the plurality of pressure sensors. The first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 in each of the pressure sensors are located in the corresponding openings, and the position of each of the openings is aligned with the first sensing electrode 101 and the second sensing electrode 201 in one of the pressure sensors.

[0078] Specifically, a plurality of first pressure-sensitive layers 103 are arranged in an array above the first substrate 100, and a plurality of second pressure-sensitive layers 203 are arranged in an array above the second substrate 200, and the shape and size of the first pressure-sensitive layer 103 are equal to the shape and size of the second pressure-sensitive layer 203, the spacing widths between any adjacent first pressure-sensitive layers 103 are equal, the spacing widths between any adjacent second pressure-sensitive layers 203 are equal, and the spacing widths between any adjacent first pressure-sensitive layers 103 are equal to the spacing widths between any adjacent second pressure-sensitive layers 203, so that the plurality of first pressure-sensitive layers 103 correspond one-to-one to the plurality of second pressure-sensitive layers 203. In the pressure sensor array, the first insulating layers 102 in any two adjacent pressure sensors are connected to each other, and the second insulating layers 202 in any two adjacent pressure sensors are connected to each other. The adhesive layer is used to bond the first insulating layer 102 and the second insulating layer 202, and the adhesive layer has the opening that penetrates the adhesive layer in a direction perpendicular to the upper surface of the first substrate 100. The first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 in each of the pressure sensors are arranged in the same opening, and the first pressure-sensitive layers 103 and the second pressure-sensitive layers 203 in a plurality of the pressure sensors are distributed in a plurality of the openings. The position of each opening is aligned with the first sensing electrode 102, the second sensing electrode 202, the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 in one of the pressure sensors in a direction perpendicular to the upper surface of the first substrate 100.

[0079] In some embodiments, the Young's modulus of the first pressure-sensitive layer 103 is equal to the Young's modulus of the second pressure-sensitive layer 203, and the Young's modulus of the adhesive layer is less than or equal to the Young's modulus of the first pressure-sensitive layer 103;

[0080] The thickness of the adhesive layer is equal to the sum of the thickness of the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 .

[0081] This embodiment increases the range of the pressure sensor by changing the contact area of ​​the microstructure between the first high modulus pressure-sensitive layer 103 and the second pressure-sensitive layer 203 (i.e., the first microstructure and the second microstructure). The pressure sensing array provided by this embodiment has an adhesive layer, which can improve the electrical stability of the pressure sensing array under high pressure and lateral shear force.

[0082] This specific embodiment also provides a method for preparing the pressure sensor array as described above. Figure 2 is a flow chart of a method for preparing a pressure sensing array in a specific embodiment of the present invention, Figure 3is a schematic diagram of the structure after forming row electrodes in a specific embodiment of the present invention, Figure 4 is a schematic diagram of the structure after the first insulating layer is formed in a specific embodiment of the present invention, Figure 5 is a schematic diagram of the structure after the first pressure-sensitive layer is formed in a specific embodiment of the present invention, Figure 6 is a schematic diagram of the structure after forming the adhesive layer in a specific embodiment of the present invention, Figure 7 Schematic diagram of the structure after the second pressure-sensitive layer is attached to the adhesive layer in a specific embodiment of the present invention. The structure of the pressure sensor in the pressure sensing array prepared in this specific embodiment is shown in FIG. Figure 1 .like Figure 1-Figure 7 As shown, the method for preparing the pressure sensing array comprises the following steps:

[0083] Step S21, providing a first substrate 100 and a second substrate 200;

[0084] Step S22, forming the row electrodes 300 on the upper surface of the first substrate 100, such as Figure 3 As shown, the column electrodes 500 are formed on the lower surface of the second substrate 200, see Figure 7 ( Figure 7 The column electrodes 500 are not visible at the angle shown, so the positions of the column electrodes 500 on the second substrate 200 are indicated by dotted lines);

[0085] Step S23, forming a first insulating layer 102 covering the row electrodes, such as Figure 4 As shown, a second insulating layer 202 is formed covering the column electrodes;

[0086] Step S24, forming a first pressure-sensitive layer 103 on the surface of the first insulating layer 102 facing away from the first substrate 100, such as Figure 5 As shown, a second pressure-sensitive layer 203 is formed on the surface of the second insulating layer 202 facing away from the second substrate 200, the first pressure-sensitive layer 103 is aligned with the second pressure-sensitive layer 203, and the size of the first pressure-sensitive layer 103 is equal to the size of the second pressure-sensitive layer 203;

[0087] Step S25, forming the adhesive layer 400 on the surface of the first insulating layer 102 facing away from the first substrate 100, wherein the adhesive layer has a plurality of openings 401 exposing the first pressure-sensitive layer 103, such as Figure 6 As shown;

[0088] Step S26, laminating the second insulating layer 202 on the adhesive layer 400 along the direction in which the second pressure-sensitive layer 203 is aligned with the first pressure-sensitive layer 103, so that the row electrodes 300 and the column electrodes 500 are arranged orthogonally, as shown in FIG. Figure 7and Figure 1 shown.

[0089] For example, the materials of the first substrate 100 and the second substrate 200 can both be polyurethane, polyimide, polyethylene terephthalate plastic, polyethylene naphthalate, polydimethylsiloxane (PDMS), polyurethane (PU) or platinum catalyzed silica gel (Ecoflex), etc., and the first substrate 100 and the second substrate 200 are both used as the bearing substrate of the pressure sensor. In this specific embodiment, the first substrate 100 and the second substrate 200 can be ultrasonically cleaned with ethanol solution, acetone solution and deionized water, and dried after cleaning, and the surfaces of the first substrate 100 and the second substrate 200 are treated with oxygen plasma or ultraviolet light / ozone.

[0090] The row electrode 300 may be divided into a plurality of first sensing electrodes 101 arranged at intervals and a first conductive connection layer located between two adjacent first sensing electrodes 101 and electrically connecting the two adjacent first sensing electrodes 101. The column electrode 500 may be divided into a plurality of second sensing electrodes 201 arranged at intervals and a second conductive connection layer located between two adjacent second sensing electrodes 201 and electrically connecting the two adjacent second sensing electrodes 201. The materials of the row electrode 300 and the column electrode 500 may both be conductive polymers, carbon-based conductive materials, metal oxides, metal nanowires, metal and metal oxide nanoparticles, and conductive pastes based on carbon-based conductive materials, metal nanowires, metal and metal oxide nanoparticles. The conductive polymer may be poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), polystyrene sulfonic acid, polyaniline, polythiophene or polypyrrole with acidic or neutral pH value, the carbon-based conductive material may be single-layer or multi-layer graphene, graphite, carbon black, single-wall or multi-wall carbon nanotube, etc., the metal may be gold, silver, copper, aluminum or nickel, and the metal oxide may be indium tin oxide or fluorine-doped tin oxide, etc. In this specific embodiment, the row electrode 300 and the column electrode 500 may be prepared by screen printing, spraying, dispensing, inkjet printing, sputtering and evaporation.

[0091] The first insulating layer 101 and the second insulating layer 201 can be made of the same material, for example, epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silica microspheres. In this specific embodiment, the first insulating layer 101 and the second insulating layer 201 can be prepared by spin coating, spray coating, scraping coating, pulling and other processes.

[0092] In one example, the material and structure of the first pressure-sensitive layer 103 are the same as the material and structure of the second pressure-sensitive layer 203. Both the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 are polymers doped with conductive nanomaterials, and the doping concentration of the conductive nanomaterials in the polymer is in the percolation region. Optionally, the doping concentration of the conductive nanomaterials is 0.5% to 10%. The conductive nanomaterials are nano-carbon powder, nano-graphite, carbon nanotubes or nano-graphene, and the polymer material is polyimide, polyvinylidene fluoride, polyurethane or polydimethylsiloxane. In this specific embodiment, the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 can be prepared by screen printing, scraping or spraying.

[0093] In some embodiments, the first pressure-sensitive layer 103 is prepared by screen printing, doctor blade coating or spray coating;

[0094] The adhesive layer 400 forms the opening 401 by laser cutting a double-sided adhesive film, and the adhesive layer 400 with the opening 401 is transferred to the surface of the first insulating layer 102; or, the adhesive layer 400 with the opening 401 is directly formed on the surface of the first insulating layer 102 by dispensing, screen printing, scraping or spraying.

[0095] Specifically, the adhesive layer 500 is used to bond the first insulating layer 102 and the second insulating layer 202. The Young's modulus of the adhesive layer 400 does not exceed the Young's modulus of the first pressure-sensitive layer 103, and the adhesive layer 400 has hollows arranged in an array at the position of the row electrode 300, that is, the adhesive layer 400 has the openings 401 arranged in an array at the position of the row electrode 300. In one example, the area of ​​each opening 401 is consistent with the area of ​​the first pressure-sensitive layer 103 in one of the pressure sensors, and the spacing between two adjacent rows of the openings 401 is consistent with the spacing between two adjacent rows of the row electrodes 300. The material of the adhesive layer 400 can be a double-sided adhesive elastic film tape, a polydimethylsiloxane (PDMS) film, a polyurethane (PU) film or a platinum-catalyzed silicone (Ecoflex) film, and the hollows of the adhesive layer 400 can be formed by laser or knife cutting, or by dispensing, screen printing, scraping or spraying on the surface of the first insulating layer 102, and then formed by heating and curing.

[0096] The second insulating layer 202 is bonded to the surface of the adhesive layer 400 to form the pressure sensor array. The column electrodes 500 are orthogonal to the row electrodes 300, and the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 are both located in the opening 401 of the adhesive layer 400. In this specific embodiment, the first insulating layer 102 and the second insulating layer 202 are bonded by using the adhesive layer 400, so that the electrical crosstalk between adjacent pressure sensors can be reduced and the electrical stability of the pressure sensor array under high pressure and lateral shear force can be improved.

[0097] The pressure sensor, pressure sensing array and preparation method thereof provided in this specific embodiment are provided by arranging closely arranged first microspheres or a first hollow film layer with a first hollow structure on the surface of the first sensing electrode, and arranging closely arranged second microspheres or a second hollow film layer with a second hollow structure on the surface of the second sensing electrode, so that the surface of the first pressure-sensitive layer and the second pressure-sensitive layer covering the surface thereof is formed with a microstructure, so that the interface contact resistance between the two sensitive layers (i.e., the first pressure-sensitive layer and the second pressure-sensitive layer) is reduced due to the increase in the contact area when the first pressure-sensitive layer or the second pressure-sensitive layer is subjected to force, thereby simultaneously achieving the effect of increasing the resistance of the sensor and reducing the power consumption of the sensor by reducing the contact area between the interface of the sensitive layer and between the sensitive layer and the electrode layer. At the same time, by adjusting the concentration of the conductive nanomaterial in the first pressure-sensitive layer and the second pressure-sensitive layer to the percolation zone, the slight thickness change of the first pressure-sensitive layer and the second pressure-sensitive layer when subjected to pressure can cause the reduction of the internal resistance of the film, thereby improving the sensitivity of the pressure sensor. In addition, this specific embodiment increases the range of the pressure sensor by changing the contact area of ​​the microstructure between the first pressure-sensitive layer and the second pressure-sensitive layer of high modulus. The pressure sensing array provided by the present invention has an adhesive layer, which can improve the electrical stability of the pressure sensing array under high pressure and lateral shear force.

[0098] The following are 6 examples of preparing the pressure sensing array.

[0099] Example 1

[0100] The pressure sensing array is prepared by the following specific steps:

[0101] (1) ultrasonically cleaning a first substrate and a second substrate both made of polyethylene terephthalate (PET) using an ethanol solution, an acetone solution, and deionized water, drying the substrate after cleaning, and treating the surfaces of the first substrate and the second substrate using oxygen plasma or ultraviolet light / ozone;

[0102] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by screen printing;

[0103] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a spin coating process;

[0104] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively; the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyimide doped with carbon nanoparticles, and the doping concentration is 3%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0105] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; attaching the double-sided adhesive tape to the surface of the first insulating layer, wherein the hollow positions of the double-sided adhesive tape overlap with the first pressure-sensitive layer;

[0106] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0107] Example 2

[0108] The pressure sensing array is prepared by the following specific steps:

[0109] (1) using an ethanol solution, an acetone solution and deionized water to ultrasonically clean a first substrate and a second substrate both made of polyimide, drying them after cleaning, and treating the surfaces of the first substrate and the second substrate with oxygen plasma or ultraviolet light / ozone;

[0110] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by inkjet printing;

[0111] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a spin coating process;

[0112] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively; the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyimide doped with nanographite particles, and the doping concentration is 5%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0113] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; attaching the double-sided adhesive tape to the surface of the first insulating layer, wherein the hollow positions of the double-sided adhesive tape overlap with the first pressure-sensitive layer;

[0114] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0115] Example 3

[0116] The pressure sensing array is prepared by the following specific steps:

[0117] (1) ultrasonically cleaning a first substrate and a second substrate both made of polyethylene naphthalate using an ethanol solution, an acetone solution, and deionized water, drying the substrate after cleaning, and treating the surfaces of the first substrate and the second substrate using oxygen plasma or ultraviolet light / ozone;

[0118] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by sputtering;

[0119] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a scraping process;

[0120] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively, wherein the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyimide doped with carbon nanotubes, and the doping concentration is 0.5%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0121] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; attaching the double-sided adhesive tape to the surface of the first insulating layer, wherein the hollow positions of the double-sided adhesive tape overlap with the first pressure-sensitive layer;

[0122] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0123] Example 4

[0124] The pressure sensing array is prepared by the following specific steps:

[0125] (1) using an ethanol solution, an acetone solution and deionized water to ultrasonically clean a first substrate and a second substrate both made of polyimide, drying them after cleaning, and treating the surfaces of the first substrate and the second substrate with oxygen plasma or ultraviolet light / ozone;

[0126] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by sputtering;

[0127] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a spin coating process;

[0128] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively; the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyimide doped with nanographite particles, and the doping concentration is 5%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0129] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; attaching the double-sided adhesive tape to the surface of the first insulating layer, wherein the hollow positions of the double-sided adhesive tape overlap with the first pressure-sensitive layer;

[0130] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0131] Example 5

[0132] The pressure sensing array is prepared by the following specific steps:

[0133] (1) using an ethanol solution, an acetone solution and deionized water to ultrasonically clean a first substrate and a second substrate both made of polyimide, drying them after cleaning, and treating the surfaces of the first substrate and the second substrate with oxygen plasma or ultraviolet light / ozone;

[0134] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by screen printing;

[0135] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a spin coating process;

[0136] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively; the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyvinylidene fluoride doped with nanographene, and the doping concentration is 3%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0137] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; attaching the double-sided adhesive tape to the surface of the first insulating layer, wherein the hollow positions of the double-sided adhesive tape overlap with the first pressure-sensitive layer;

[0138] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0139] Example 6

[0140] The pressure sensing array is prepared by the following specific steps:

[0141] (1) using an ethanol solution, an acetone solution and deionized water to ultrasonically clean a first substrate and a second substrate both made of polyimide, drying them after cleaning, and treating the surfaces of the first substrate and the second substrate with oxygen plasma or ultraviolet light / ozone;

[0142] (2) preparing row electrodes and column electrodes on the upper and lower surfaces of the first substrate and the second substrate respectively by inkjet printing;

[0143] (3) preparing a polystyrene microsphere layer (i.e., the first insulating layer and the second insulating layer) on the surface of the row electrode and the column electrode by a spin coating process;

[0144] (4) using a screen printing process to prepare a first pressure-sensitive layer and a second pressure-sensitive layer on the surfaces of the first insulating layer and the second insulating layer, respectively; the material of the first pressure-sensitive layer and the material of the second pressure-sensitive layer are both polyvinylidene fluoride doped with nanographene, and the doping concentration is 10%; the first pressure-sensitive layer and the second pressure-sensitive layer are both aligned and overlapped with the column electrode and the row electrode;

[0145] (5) forming an array of hollow (i.e., the opening) patterns on the surface of the double-sided adhesive tape (i.e., the adhesive layer) by laser cutting, wherein the spacing of the hollow patterns is consistent with the spacing of the row / column electrodes; attaching the double-sided adhesive tape to the surface of the row / column electrodes, wherein the hollow positions of the double-sided adhesive tape overlap with the patterned pressure-sensitive layer;

[0146] (6) The second substrate is bonded to the double-sided adhesive surface, and the second pressure-sensitive layer on the second substrate overlaps with the hollowed-out position (ie, the opening position) of the adhesive layer on the first substrate.

[0147] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pressure sensor, characterized in that: include: A first substrate, comprising an upper surface and a lower surface that are oppositely distributed; A first sensing electrode, located on the upper surface of the first substrate; A first insulating layer is located on a surface of the first sensing electrode facing away from the first substrate, the first insulating layer includes a plurality of first microspheres arranged in an array or the first insulating layer is a first hollow film layer having a first hollow structure; A first piezoresistive layer is located on a surface of the first insulating layer facing away from the first substrate, the first piezoresistive layer is also filled in a first gap in the first insulating layer and is in contact with and connected to the first sensing electrode, the first gap is located between adjacent first microspheres or the first gap is the first hollow structure, and the first piezoresistive layer is a first piezoresistive film layer having a first microstructure on a surface facing away from the first substrate; a second substrate, located above the first substrate, the second substrate comprising an upper surface and a lower surface that are oppositely distributed, and the lower surface of the second substrate is arranged toward the upper surface of the first substrate; A second sensing electrode is located on the lower surface of the second substrate; A second insulating layer is located on a surface of the second sensing electrode facing away from the second substrate, the second insulating layer includes a plurality of second microspheres arranged in an array or the second insulating layer is a second hollow film layer having a second hollow structure; The second piezoresistive layer is located on the surface of the second insulating layer facing away from the second substrate. The second piezoresistive layer also fills the second gap in the second insulating layer and is in contact with the second sensing electrode. The second gap is located between adjacent second microspheres or the second gap is the second hollow structure. The second piezoresistive layer is a second piezoresistive film layer having a second microstructure on the surface facing away from the second substrate.

2. The pressure sensor according to claim 1, characterized in that: The material of the first piezoresistive film layer and the material of the second piezoresistive film layer are both polymers doped with conductive nanomaterials. The doping concentration of the conductive nanomaterials in the polymers is in the percolation region, and the doping concentration is 0.5% to 10%.

3. The pressure sensor according to claim 1, characterized in that: The plurality of the first microspheres in the first insulating layer are arranged in a single-layer array, and the plurality of the second microspheres in the second insulating layer are also arranged in a single-layer array; The first microspheres in the first insulating layer have the same size or the first insulating layer includes the first microspheres of two sizes; The sizes of the plurality of second microspheres in the second insulating layer are the same or the second insulating layer includes two second microspheres of different sizes; The size of the first microsphere and the diameter of the second microsphere are both 0.1 micrometer to 10 micrometers.

4. The pressure sensor according to claim 1, characterized in that: The material of the first microsphere is the same as that of the second microsphere, and both are epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silicon dioxide.

5. The pressure sensor according to claim 1, characterized in that: The shape of the first hollow structure is the same as the shape of the second hollow structure, both of which are round or square; The distance between adjacent first hollow structures in the first insulating layer is 10 micrometers to 100 micrometers, and the distance between adjacent second hollow structures in the second insulating layer is 10 micrometers to 100 micrometers.

6. The pressure sensor according to claim 1, characterized in that: The material of the first sensing electrode and the material of the second sensing electrode are any one of conductive polymers, carbon-based conductors, metal oxides, metal nanowires, metal and metal oxide nanoparticles, and conductive pastes based on carbon-based conductors, metal nanowires, metal and metal oxide nanoparticles.

7. A pressure sensing array, characterized in that: include: A plurality of pressure sensors according to any one of claims 1 to 6, wherein the plurality of pressure sensors are arranged in an array; The first sensing electrodes in the plurality of pressure sensors arranged in the same row are electrically connected and collectively serve as row electrodes; The second sensing electrodes in the plurality of pressure sensors arranged in the same column are electrically connected and collectively serve as column electrodes, and the column electrodes are arranged orthogonally to the row electrodes; The pressure sensing array also includes an adhesive layer, which is sandwiched between the first insulating layer and the second insulating layer. The adhesive layer has a plurality of openings corresponding to the plurality of pressure sensors. The first pressure-sensitive layer and the second pressure-sensitive layer in each of the pressure sensors are located in the corresponding openings, and the position of each of the openings is aligned with the first sensing electrode and the second sensing electrode in one of the pressure sensors.

8. The pressure sensing array according to claim 7, characterized in that: The Young's modulus of the first pressure-sensitive layer is equal to the Young's modulus of the second pressure-sensitive layer, and the Young's modulus of the adhesive layer is less than or equal to the Young's modulus of the first pressure-sensitive layer; The thickness of the adhesive layer is equal to the sum of the thicknesses of the first pressure-sensitive layer and the second pressure-sensitive layer.

9. A method for preparing a pressure sensing array as claimed in claim 7, characterized in that: The steps include: providing a first substrate and a second substrate; forming the row electrodes on the upper surface of the first substrate, and forming the column electrodes on the lower surface of the second substrate; forming a first insulating layer covering the row electrodes, and forming a second insulating layer covering the column electrodes; Forming a first pressure-sensitive layer on a surface of the first insulating layer facing away from the first substrate, and forming a second pressure-sensitive layer on a surface of the second insulating layer facing away from the second substrate, wherein the first pressure-sensitive layer is aligned with the second pressure-sensitive layer, and the size of the first pressure-sensitive layer is equal to the size of the second pressure-sensitive layer; forming the adhesive layer on the surface of the first insulating layer facing away from the first substrate, wherein the adhesive layer has a plurality of openings exposing the first pressure-sensitive layer; The second insulating layer is laminated on the adhesive layer along the direction in which the second pressure-sensitive layer is aligned with the first pressure-sensitive layer, so that the row electrodes and the column electrodes are arranged orthogonally.

10. The method for preparing a pressure sensing array according to claim 9, characterized in that: The first pressure-sensitive layer is prepared by screen printing, doctor blade coating or spray coating; The adhesive layer forms the opening by laser cutting a double-sided adhesive film, and the adhesive layer forming the opening is transferred to the surface of the first insulating layer; Alternatively, the adhesive layer having the opening is directly formed on the surface of the first insulating layer by dispensing, screen printing, scraping or spraying.

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