Pressure sensor, pressure sensor array, and method for manufacturing the same

Abstract

The application relates to a pressure sensor, a pressure sensing array and a preparation method thereof. The pressure sensor comprises a first substrate, a first sensing electrode located on the upper surface of the first substrate, a first insulating layer located on the surface of the first sensing electrode and comprising a plurality of first microspheres arranged in an array or being a first hollow membrane layer, a first pressure sensitive layer located on the surface of the first insulating layer and filled into the first interspace in the first insulating layer, a second substrate located above the first substrate, a second sensing electrode located on the lower surface of the second substrate, a second insulating layer located on the surface of the second sensing electrode, the second insulating layer comprising a plurality of second microspheres arranged in an array or being a second hollow membrane layer, and a second pressure sensitive layer located on the surface of the second insulating layer and filled into the second interspace in the second insulating layer. The pressure sensor provided by the application has higher sensitivity under high pressure and thin thickness.

Description

Technical Field

[0001] This invention relates to the field of sensing technology, and in particular to a pressure sensor, a pressure sensing array, and a method for fabricating the same. Background Technology

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

[0003] Currently, research on flexible pressure sensors can be based on various working principles, mainly including capacitive, resistive, piezoelectric, and thin-film transistor (TFT) types. Among them, resistive pressure sensors are widely used due to their simple structure and immunity to external electromagnetic interference. However, reducing the thickness of the sensitive thin film in resistive pressure sensors leads to a decrease in sensitivity due to the increased sensing range.

[0004] Therefore, how to improve the sensitivity and sensing range of resistive pressure sensors while reducing their thickness is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This invention provides a pressure sensor, a pressure sensing array, and a method for fabricating the same, to address the problem that current ultra-thin pressure sensors cannot simultaneously achieve high sensitivity and a large sensing range, thereby improving the performance of pressure sensors and expanding their application areas.

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

[0007] The first substrate includes an upper surface and a lower surface that are distributed opposite to each other;

[0008] The first sensing electrode is located on the upper surface of the first substrate;

[0009] A first insulating layer is located on the surface of the first sensing electrode 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 perforated film layer with a first perforated structure.

[0010] The first pressure-sensitive layer is located on the surface of the first insulating layer away from the first substrate. The first pressure-sensitive layer is also filled in the first void in the first insulating layer and is in contact with the first sensing electrode. The first void is located between adjacent first microspheres or the first void is the first hollow structure. The first pressure-sensitive layer is a first piezoresistive film layer with a first microstructure on the surface away from the first substrate.

[0011] A second substrate is located above the first substrate. The second substrate includes an upper surface and a lower surface that are distributed opposite to each other, with the lower surface of the second substrate facing the upper surface of the first substrate.

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

[0013] The second insulating layer is located on the surface of the second sensing electrode 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 perforated film layer with a second perforated structure.

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

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

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

[0017] The first insulating layer contains multiple first microspheres of the same size, or the first insulating layer includes first microspheres of two different sizes;

[0018] The second insulating layer contains multiple second microspheres of the same size, or the second insulating layer includes two different sizes of second microspheres.

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

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

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

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

[0023] In some embodiments, the materials of the first sensing electrode and the second sensing electrode are both 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.

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

[0025] Multiple pressure sensors as described above, and the multiple pressure sensors are arranged in an array;

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

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

[0028] The pressure sensing array further includes an adhesive layer sandwiched between the first insulating layer and the second insulating layer. The adhesive layer has multiple openings that correspond one-to-one with the multiple pressure sensors. The first pressure-sensitive layer and the second pressure-sensitive layer in each pressure sensor are located in their corresponding openings, and the position of each opening 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 and the Young's modulus of the second pressure-sensitive layer are equal, 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 other embodiments, the present invention also provides a method for fabricating the pressure sensing array as described above, comprising the following steps:

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

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

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

[0035] A first pressure-sensitive layer is formed on the surface of the first insulating layer opposite to the first substrate, and a second pressure-sensitive layer is formed on the surface of the second insulating layer opposite to the second substrate. The first pressure-sensitive layer and the second pressure-sensitive layer are aligned, and the size of the first pressure-sensitive layer is equal to the size of the second pressure-sensitive layer.

[0036] The adhesive layer is formed on the surface of the first insulating layer opposite to the first substrate, and the adhesive layer has a plurality of openings exposing the first pressure-sensitive layer;

[0037] The second insulating layer is attached to 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 orthogonally arranged.

[0038] In some embodiments, the first pressure-sensitive layer is prepared by screen printing, scraping or spraying.

[0039] The opening is formed in the adhesive layer by laser cutting of the 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 formed directly on the surface of the first insulating layer by dispensing, screen printing, scraping or spraying.

[0040] The pressure sensor, pressure sensing array, and fabrication method provided by this invention, by setting a first microsphere or a first perforated film layer with a first perforated structure on the surface of a first sensing electrode, and a second microsphere or a second perforated film layer with a second perforated structure on the surface of a second sensing electrode, microstructures are formed on the surfaces of the first and second pressure-sensitive layers covering them. This causes the interfacial contact resistance between the two sensitive layers (i.e., the first and second pressure-sensitive layers) to decrease due to the increased contact area when the first or second pressure-sensitive layer is subjected to force. This simultaneously increases the sensor's resistance and reduces its power consumption by reducing the contact area between the interfaces of the sensitive layers and between the sensitive layer and the electrode layer. Furthermore, by adjusting the concentration of conductive nanomaterials in the first and second pressure-sensitive layers to the percolation region, even slight changes in the thickness of the first and second pressure-sensitive layers under pressure can cause a decrease in the internal resistance of the film, thereby improving the sensitivity of the pressure sensor. Additionally, this invention increases the range of the pressure sensor by changing the contact area of ​​the microstructure between the high-modulus first and second pressure-sensitive layers. The pressure sensing array provided by this invention contains an adhesive layer, which can improve the electrical stability of the pressure sensing array under high pressure and lateral shear force. Attached Figure Description

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

[0042] Figure 2 This is a flowchart of the preparation method of the pressure sensing array in a specific embodiment of the present invention;

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

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

[0045] Figure 5 This 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 This is a schematic diagram of the structure after the adhesive layer is formed in a specific embodiment of the present invention;

[0047] Figure 7 This 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 Implementation

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

[0049] This specific embodiment provides a pressure sensor. Figure 1 This is a cross-sectional schematic diagram of the pressure sensor in a specific embodiment of the present invention. For example... Figure 1 As shown, the pressure sensor includes:

[0050] The first substrate 100 includes an upper surface and a lower surface that are distributed relative to each other;

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

[0052] The first insulating layer 102 is located on the surface of the first sensing electrode 101 away from the first substrate 100. 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.

[0053] The first pressure-sensitive layer 103 is located on the surface of the first insulating layer 102 away from the first substrate 100. The first pressure-sensitive layer 103 is also filled in the 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 pressure-sensitive layer 103 is a first piezoresistive film layer with a first microstructure on the surface away from the first substrate 100.

[0054] The second substrate 200 is located above the first substrate 100. The second substrate 200 includes an upper surface and a lower surface that are distributed opposite to each other. The lower surface of the second substrate 200 is disposed facing the upper surface of the first substrate 100.

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

[0056] The second insulating layer 202 is located on the surface of the second sensing electrode 201 away from the second substrate 200. 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 with a second hollow structure.

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

[0058] Specifically, such as Figure 1As shown, the first substrate 100 includes an upper surface and a lower surface that are relatively distributed. The second substrate 200 also includes an upper surface and a lower surface that are relatively 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 comprises a plurality of first microspheres arranged in an array, or the first insulating layer 102 is a first perforated film layer with a first perforated structure, thereby creating voids in the first insulating layer 102, i.e., the first voids, and making the surface of the first insulating layer 102 facing away from the first substrate 100 a rough surface with a regular structure. Since a portion of the first pressure-sensitive layer 103 fills the first voids, the surface of the first pressure-sensitive layer 103 facing away from the first substrate 100 is not flat, i.e., the first microstructure is formed on the surface of the first pressure-sensitive layer 103 facing away from the first substrate 100. The second insulating layer 202 comprises a plurality of second microspheres arranged in an array, or the second insulating layer 202 is a second perforated film layer with a second perforated structure, thereby creating voids in the second insulating layer 202, i.e., the second voids, and making the surface of the second insulating layer 202 facing away from the second substrate 200 a rough surface with a regular structure. Because a portion of the second pressure-sensitive layer 103 fills the second void, the surface of the second pressure-sensitive layer 203 facing away from the second substrate 200 is not flat, i.e., 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 both the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 is 15 micrometers to 100 micrometers.

[0059] Due to the presence of the first and second microstructures, when the pressure sensor receives external pressure, the contact area between the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 changes, thereby altering the interfacial contact resistance between them. This simultaneously increases the resistance of the pressure sensor and reduces its power consumption by decreasing the contact areas 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 between the sensitive layer and the electrode layers (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 embodiment is not limited by the thickness of the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203, thus simultaneously possessing high sensitivity and a large sensing range, thereby improving the performance of the pressure sensor.

[0060] In one example, both the first substrate 100 and the second substrate 200 serve as the carrier substrates of the pressure sensor. The materials of the first substrate 100 and the second substrate 200 can both be polyurethane, polyimide, polyethylene terephthalate, polyethylene naphthalate, polydimethylsiloxane, polyurethane, or platinum-catalyzed silica gel.

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

[0062] For example, the conductive nanomaterial is carbon nanoparticles, graphite nanoparticles, carbon nanotubes, or graphene nanoparticles, 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 nanomaterials in the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 is located in the percolation region. Under external pressure, the spacing between the conductive nanomaterials decreases, causing an increase in conductivity. Simultaneously, the microstructures on the surfaces of the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 are arranged opposite each other, and the area of ​​the microstructure interface increases under 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 insulating layer 102 may contain multiple first microspheres of the same size or may contain two sizes of first microspheres.

[0065] The second insulating layer 202 may contain multiple second microspheres of the same size or may contain two different sizes of second microspheres.

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

[0067] Specifically, both the first insulating layer 102 and the second insulating layer 202 are either closely packed monolayer microspheres or perforated films formed by photolithography. Gaps exist between the closely packed microspheres, and perforated structures exist within the perforated film. These gaps and perforated structures give the first insulating layer 102 and the second insulating layer 202 rough surfaces, which are rough surfaces with regular structures. The gaps between the closely packed microspheres and the perforated structures also provide a connection channel between the pressure-sensitive layer (e.g., the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203) and the sensing electrodes (e.g., the first sensing electrode 101 and the second sensing electrode 201). In one example, the plurality of first microspheres in the first insulating layer 102 are solid microspheres of one or two sizes, and the plurality of second microspheres in the second insulating layer 202 are also solid microspheres of one or two sizes. 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 first microsphere and the second microsphere are made of the same material, namely epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silicon dioxide.

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

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

[0071] In some embodiments, the materials of the first sensing electrode 101 and the second sensing electrode 201 are all 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.

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

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

[0074] Multiple pressure sensors as described above (see Figure 1 Furthermore, the pressure sensors are arranged in an array.

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

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

[0077] The pressure sensing array further includes an adhesive layer sandwiched between the first insulating layer 102 and the second insulating layer 202. The adhesive layer has multiple openings corresponding to the multiple pressure sensors. The first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 in each pressure sensor are located in their corresponding openings, and the position of each opening 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. The shape and size of the first pressure-sensitive layers 103 are equal to the shape and size of the second pressure-sensitive layers 203. The spacing between any two adjacent first pressure-sensitive layers 103 is equal, and the spacing between any two adjacent second pressure-sensitive layers 203 is equal to the spacing between any two adjacent first pressure-sensitive layers 103, so that there is a one-to-one correspondence between the plurality of first pressure-sensitive layers 103 and the plurality of second pressure-sensitive layers 203. In the pressure sensor array, the first insulating layers 102 of any two adjacent pressure sensors are interconnected, and the second insulating layers 202 of any two adjacent pressure sensors are interconnected. The adhesive layer is used to bond the first insulating layer 102 and the second insulating layer 202, and the adhesive layer has an opening penetrating 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 pressure sensor are disposed in the same opening, and the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 in multiple pressure sensors are distributed in multiple 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 pressure sensor 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 and the Young's modulus of the second pressure-sensitive layer 203 are equal, 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 thicknesses of the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203.

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

[0082] This specific embodiment also provides a method for fabricating the pressure sensing array as described above. Figure 2 This is a flowchart illustrating the fabrication method of the pressure sensing array in a specific embodiment of the present invention. Figure 3This is a schematic diagram of the structure after the row electrodes are formed in a specific embodiment of the present invention. Figure 4 This is a schematic diagram of the structure after the first insulating layer is formed in a specific embodiment of the present invention. Figure 5 This 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 This is a schematic diagram of the structure after the adhesive layer is formed in a specific embodiment of the present invention. Figure 7 This is a schematic diagram of the structure after the second pressure-sensitive layer is bonded 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 below. Figure 1 .like Figures 1-7 As shown, the method for fabricating the pressure sensing array includes the following steps:

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

[0084] Step S22, forming the row electrode 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 [reference]. Figure 7 ( Figure 7 (The column electrode 500 is not visible at the angle shown, so the position of the column electrode 500 on the second substrate 200 is indicated by a dashed line);

[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 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, the adhesive layer having a plurality of openings 401 exposing the first pressure-sensitive layer 103, such as... Figure 6 As shown;

[0088] Step S26: The second insulating layer 202 is adhered to the adhesive layer 400 along the direction in which the second pressure-sensitive layer 203 is aligned with the first pressure-sensitive layer 103, such that the row electrodes 300 and the column electrodes 500 are orthogonally arranged. Figure 7and Figure 1 As shown.

[0089] For example, the materials of the first substrate 100 and the second substrate 200 can both be polyurethane, polyimide, polyethylene terephthalate, polyethylene naphthalate, polydimethylsiloxane (PDMS), polyurethane (PU), or platinum-catalyzed silica gel (Ecoflex), etc., and both the first substrate 100 and the second substrate 200 serve as the carrier substrate of the pressure sensor. In this specific embodiment, the first substrate 100 and the second substrate 200 can be ultrasonically cleaned using an ethanol solution, an acetone solution, and deionized water. After cleaning and drying, 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 can be divided into a plurality of first sensing electrodes 101 arranged at intervals and a first conductive connection layer located between and electrically connecting two adjacent first sensing electrodes 101. The column electrode 500 can be divided into a plurality of second sensing electrodes 201 arranged at intervals and a second conductive connection layer located between and electrically connecting two adjacent second sensing electrodes 201. The materials of the row electrode 300 and the column electrode 500 can 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 can be pH-acidic or neutral poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), polystyrene sulfonic acid, polyaniline, polythiophene, or polypyrrole. The carbon-based conductive material can be single-layer or multi-layer graphene, graphite, carbon black, single-walled or multi-walled carbon nanotubes, etc. The metal can be gold, silver, copper, aluminum, or nickel. The metal oxide can be indium tin oxide or fluorine-doped tin oxide, etc. In this specific embodiment, both the row electrode 300 and the column electrode 500 can be prepared by methods such as 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, such as epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate, or silica microspheres. In this specific embodiment, both the first insulating layer 101 and the second insulating layer 201 can be prepared using processes such as spin coating, spray coating, blade coating, or dip coating.

[0092] In one example, the material and structure of the first pressure-sensitive layer 103 are the same as those 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 located in the percolation region. Optionally, the doping concentration of the conductive nanomaterials is 0.5% to 10%. The conductive nanomaterials are carbon nanoparticles, graphite nanoparticles, carbon nanotubes, or graphene nanoparticles, and the polymer material is polyimide, polyvinylidene fluoride, polyurethane, or polydimethylsiloxane. In this specific embodiment, both the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 can be prepared by screen printing, blade coating, or spray coating methods.

[0093] In some embodiments, the first pressure-sensitive layer 103 is prepared by screen printing, scraping or spraying.

[0094] The adhesive layer 400 forms the opening 401 by laser cutting a double-sided adhesive film, and the adhesive layer 400 forming the opening 401 is transferred to the surface of the first insulating layer 102; or, the adhesive layer 400 with the opening 401 is formed directly 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. The adhesive layer 400 has an array of cutouts at the row electrode 300 positions, that is, the adhesive layer 400 has an array of openings 401 at the row electrode 300 positions. In one example, the area of ​​each opening 401 is consistent with the area of ​​the first pressure-sensitive layer 103 in one pressure sensor, and the spacing between two adjacent rows of openings 401 is consistent with the spacing between two adjacent rows of row electrodes 300. The adhesive layer 400 material can be double-sided adhesive elastic film tape, polydimethylsiloxane (PDMS) film, polyurethane (PU) film, or platinum catalytic silicone (Ecoflex) film. The cutouts of the adhesive layer 400 can be formed by laser, tool cutting, or by applying adhesive, screen printing, scraping, or spraying to the surface of the first insulating layer 102 and then curing it by heat.

[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 and the row electrodes 300 are orthogonal to each other, and both the first pressure-sensitive layer 103 and the second pressure-sensitive layer 203 are located in the opening 401 of the adhesive layer 400. In this specific embodiment, by using the adhesive layer 400 to bond the first insulating layer 102 and the second insulating layer 202, 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 fabrication method provided in this specific embodiment achieve the following: First, a first microsphere or a first perforated film layer with a first perforated structure is densely arranged on the surface of a first sensing electrode; second, a second microsphere or a second perforated film layer with a second perforated structure is densely arranged on the surface of a second sensing electrode. This creates a microstructure on the surfaces of the first and second pressure-sensitive layers, causing the interfacial contact resistance between the two sensitive layers (i.e., the first and second pressure-sensitive layers) to decrease due to the increased contact area when the first or second pressure-sensitive layer is subjected to force. This simultaneously increases the sensor's resistance and reduces its power consumption by reducing the contact area between the interfaces of the sensitive layers and between the sensitive layer and the electrode layer. Furthermore, by adjusting the concentration of conductive nanomaterials in the first and second pressure-sensitive layers to the percolation region, even slight changes in the thickness of the first and second pressure-sensitive layers under pressure can cause a decrease in the film's internal resistance, thereby improving the sensitivity of the pressure sensor. Additionally, this specific embodiment increases the range of the pressure sensor by changing the contact area of ​​the microstructure between the high-modulus first and second pressure-sensitive layers. The pressure sensing array provided by this invention contains 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 six embodiments for fabricating the pressure sensing array.

[0099] Example 1

[0100] The pressure sensing array is fabricated through the following specific steps:

[0101] (1) The first and second substrates, both made of polyethylene terephthalate (PET), were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0103] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by spin coating process;

[0104] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the material of the second varistor layer are both polyimide doped with carbon nanoparticles, and the doping concentration is 3%. The first varistor layer and the second varistor layer are aligned and coincident with the column electrode and the row electrode.

[0105] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; the double-sided adhesive is attached to the surface of the first insulating layer, and the hollow position of the double-sided adhesive coincides with the first pressure-sensitive layer.

[0106] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0107] Example 2

[0108] The pressure sensing array is fabricated through the following specific steps:

[0109] (1) The first and second substrates, both made of polyimide, were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0111] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by spin coating process;

[0112] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the material of the second varistor layer are both polyimide doped with nano-graphite particles, and the doping concentration is 5%. The first varistor layer and the second varistor layer are aligned and coincident with the column electrode and the row electrode.

[0113] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; the double-sided adhesive is attached to the surface of the first insulating layer, and the hollow position of the double-sided adhesive coincides with the first pressure-sensitive layer.

[0114] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0115] Example 3

[0116] The pressure sensing array is fabricated through the following specific steps:

[0117] (1) The first and second substrates, both made of polyethylene naphthalate, were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0119] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by a blade coating process;

[0120] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the second varistor layer are both polyimide doped with carbon nanotubes, and the doping concentration is 0.5%. The first varistor layer and the second varistor layer are aligned and overlapped with the column electrode and the row electrode.

[0121] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; the double-sided adhesive is attached to the surface of the first insulating layer, and the hollow position of the double-sided adhesive coincides with the first pressure-sensitive layer.

[0122] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0123] Example 4

[0124] The pressure sensing array is fabricated through the following specific steps:

[0125] (1) The first and second substrates, both made of polyimide, were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0127] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by spin coating process;

[0128] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the material of the second varistor layer are both polyimide doped with nano-graphite particles, and the doping concentration is 5%. The first varistor layer and the second varistor layer are aligned and coincident with the column electrode and the row electrode.

[0129] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; the double-sided adhesive is attached to the surface of the first insulating layer, and the hollow position of the double-sided adhesive coincides with the first pressure-sensitive layer.

[0130] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0131] Example 5

[0132] The pressure sensing array is fabricated through the following specific steps:

[0133] (1) The first and second substrates, both made of polyimide, were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0135] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by spin coating process;

[0136] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the material of the second varistor layer are both polyvinylidene fluoride doped with nano-graphene, and the doping concentration is 3%. The first varistor layer and the second varistor layer are aligned and overlapped with the column electrode and the row electrode.

[0137] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row electrodes and the spacing of the column electrodes; the double-sided adhesive is attached to the surface of the first insulating layer, and the hollow position of the double-sided adhesive coincides with the first pressure-sensitive layer.

[0138] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0139] Example 6

[0140] The pressure sensing array is fabricated through the following specific steps:

[0141] (1) The first and second substrates, both made of polyimide, were ultrasonically cleaned using ethanol solution, acetone solution and deionized water. After cleaning and drying, the surfaces of the first and second substrates were treated with oxygen plasma or ultraviolet light / ozone.

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

[0143] (3) Polystyrene microspheres (i.e., the first insulating layer and the second insulating layer) are prepared on the surface of the row electrode and the column electrode by spin coating process;

[0144] (4) A first varistor layer and a second varistor layer are prepared on the surfaces of the first insulating layer and the second insulating layer respectively by screen printing process. The material of the first varistor layer and the material of the second varistor layer are both polyvinylidene fluoride doped with nano-graphene, and the doping concentration is 10%. The first varistor layer and the second varistor layer are aligned and overlapped with the column electrode and the row electrode.

[0145] (5) An array of hollow patterns (i.e., openings) are formed on the surface of the double-sided adhesive (i.e., the adhesive layer) by laser cutting, and the spacing of the hollow patterns is consistent with the spacing of the row / column electrodes; the double-sided adhesive is attached to the surface of the row / column electrodes, and the hollow position of the double-sided adhesive coincides with the patterned pressure-sensitive layer.

[0146] (6) The second substrate is attached to the surface of the double-sided adhesive, and the second pressure-sensitive layer on the second substrate coincides with the cutout position (i.e. the opening position) of the adhesive layer on the first substrate.

[0147] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pressure sensor, characterized by The pressure sensor comprises: a first substrate comprising oppositely distributed upper and lower surfaces; a first sensing electrode located on the upper surface of the first substrate; a first insulating layer located on the surface of the first sensing electrode away from the first substrate, the first insulating layer comprising a plurality of first microspheres arranged in an array or the first insulating layer being a first hollow film layer having a first hollow structure; a first pressure-sensitive layer located on the surface of the first insulating layer away from the first substrate, the first pressure-sensitive layer also filling a first void in the first insulating layer and being in contact with the first sensing electrode, the first void being located between adjacent first microspheres or the first void being the first hollow structure, the first pressure-sensitive layer being a first piezoresistive film layer having a first microstructure on the surface away from the first substrate; a second substrate located above the first substrate, the second substrate comprising oppositely distributed upper and lower surfaces, the lower surface of the second substrate being arranged towards the upper surface of the first substrate; a second sensing electrode located on the lower surface of the second substrate; a second insulating layer located on the surface of the second sensing electrode away from the second substrate, the second insulating layer comprising a plurality of second microspheres arranged in an array or the second insulating layer being a second hollow film layer having a second hollow structure; a second pressure-sensitive layer located on the surface of the second insulating layer away from the second substrate, the second pressure-sensitive layer also filling a second void in the second insulating layer and being in contact with the second sensing electrode, the second void being located between adjacent second microspheres or the second void being the second hollow structure, the second pressure-sensitive layer being a second piezoresistive film layer having a second microstructure on the surface away from the second substrate, the first microstructure on the surface of the first pressure-sensitive layer being oppositely arranged with the second microstructure on the surface of the second pressure-sensitive layer, and the first pressure-sensitive layer being in direct contact with the second pressure-sensitive layer, when the pressure sensor is subjected to external pressure, the contact area between the first pressure-sensitive layer and the second pressure-sensitive layer changes.

2. The pressure sensor of claim 1, wherein, 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 of claim 1, wherein, The plurality of first microspheres in the first insulating layer are arranged in a single-layer array, and the plurality of second microspheres in the second insulating layer are also arranged in a single-layer array. The plurality of first microspheres in the first insulating layer are of the same size or the first insulating layer comprises two sizes of first microspheres. The plurality of second microspheres in the second insulating layer are of the same size or the second insulating layer comprises two sizes of second microspheres. The size of the first microspheres and the diameter of the second microspheres are both 0.1 microns to 10 microns.

4. The pressure sensor of claim 1, wherein, The material of the first microspheres and the material of the second microspheres are the same, and are epoxy resin, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate or silicon dioxide.

5. The pressure sensor of claim 1, wherein, The shape of the first hollow structure and the shape of the second hollow structure are the same, and are circular or square; The distance between adjacent first hollow structures in the first insulating layer is 10-100 microns, and the distance between adjacent second hollow structures in the second insulating layer is 10-100 microns.

6. The pressure sensor of claim 1, wherein, The material of the first sensing electrode and the material of the second sensing electrode are any one of conductive polymers, carbon-based conductive materials, metal oxides, metal nanowires, metal and metal oxide nanoparticles, and conductive paste based on carbon-based conductive materials, metal nanowires, metal and metal oxide nanoparticles.

7. A pressure sensing array, characterized by, Comprising: A plurality of pressure sensors as claimed in any one of claims 1-6, and 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 and the row electrodes are arranged orthogonally; The pressure sensor array further comprises an adhesive layer, which is sandwiched between the first insulating layer and the second insulating layer, and 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 pressure sensor are located in the corresponding opening, and the position of each opening is aligned with the first sensing electrode and the second sensing electrode in one pressure sensor.

8. The pressure sensing array of claim 7, wherein, The Young's modulus of the first pressure-sensitive layer and the Young's modulus of the second pressure-sensitive layer are equal, 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 of fabricating a pressure sensor array as claimed in claim 7, characterized in that, Comprising the following steps: 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 the surface of the first insulating layer away from the first substrate and forming a second pressure-sensitive layer on the surface of the second insulating layer away from the second substrate, 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 away from the first substrate, the adhesive layer has a plurality of openings exposing the first pressure-sensitive layer; Attaching the second insulating layer to the adhesive layer in the direction aligned with the second pressure-sensitive layer and the first pressure-sensitive layer, so that the row electrodes and the column electrodes are arranged orthogonally.

10. The method of claim 9, wherein the pressure sensing array is prepared by, The first pressure-sensitive layer is prepared by screen printing, blade coating or spraying; The adhesive layer forms the openings by laser cutting a double-sided adhesive film, and transfers the adhesive layer with the openings to the surface of the first insulating layer; Alternatively, the adhesive layer with the opening is formed directly on the surface of the first insulating layer by means of dispensing, screen printing, doctor blading or spraying.

Images