Thin film pressure sensor and preparation method thereof

Abstract

The present invention relates to the field of piezoresistive sensing technology, and in particular to a thin film pressure sensor and a preparation method thereof. The preparation method comprises the following steps: forming at least a portion of a non-completely conductive layer on one surface of a piezoresistive film layer, and forming a conductive film layer by screen printing on the other surface; screen printing a conductive paste on the surface of the non-completely conductive layer, and performing a drying process to form at least a conductive film layer on the surface of the non-completely conductive layer; or, forming a layer of non-completely conductive layer on two opposite surfaces of the piezoresistive film layer, and screen printing a conductive paste on the surface of each layer of the non-completely conductive layer, and performing a drying process to form at least a portion of a conductive film layer on the surface of each layer of the non-completely conductive layer. The preparation method of the present invention can effectively solve the tunneling path problem that occurs when the layer structure of the thin film pressure sensor is reduced, and the resulting sensor is relatively thin and has good piezoresistive detection characteristics.

Description

[Technical field]

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

[0002] The resistive strain sensor is mainly composed of three parts: substrate, pressure-sensitive layer, and electrode. It generally includes a first temperature-resistant film, a first electrode layer, a piezoresistive film layer, a second electrode layer, and a second temperature-resistant film stacked in sequence. The first temperature-resistant film and the second temperature-resistant film play the role of reliability and functional modules at the same time. In addition to being the substrate of the electrode, the two layers of temperature-resistant film also have the function of protecting the piezoresistive film layer and the function of contacting the material. Several functions are coupled together, which greatly reduces the selection of materials, which also affects the diversity of appearance and touch. More importantly, due to the different hardness and curvature radius of the material, stress concentration is prone to occur on the inner surface of the resistive strain sensor during bending and use, resulting in wrinkles and local arching, and the introduction of water vapor and debris accompanied by degumming, which eventually leads to water absorption and degeneration of the sensor, oxidation of the electrode, and even short circuit or open circuit.

[0003] The prior art generally reduces the hardness and improves the bending performance by reducing the number of layer structures of the resistive strain sensor. However, reducing the number of layer structures will cause tunneling path phenomenon. Figure 1 As shown in the figure, the so-called tunneling path is that the piezoresistive film layer includes base material (light gray dots) and conductive particles (dark gray dots). When the cross section is randomly distributed, long chains formed by adjacent conductive particles will appear to form a conductive channel, so that there is a pair of special contact points AB (A'-B') on the two opposite sides of the piezoresistive film layer, and the resistance between them is a fixed value R0. At this time, a pair of non-special contact points CD are randomly selected, and the expected resistance between them is R1, and R0 is much smaller than R1. Since all special contact points AB (A'-B') must be connected, there are a large number of conductive channels in the parallel circuit, and the variable resistance signal generated by the piezoresistive effect is submerged by the conductive path with lower resistance, and piezoresistive detection cannot be performed.

[0004] Based on the above defects, it is necessary to provide a new technical solution to solve the above technical problems existing in the existing thin film pressure sensor. [Summary of the invention]

[0005] One of the purposes of the present invention is to provide a method for preparing a thin film pressure sensor to solve the problem that the existing thin film pressure sensor cannot perform piezoresistive detection due to the tunneling path phenomenon when the layer structure is thinned.

[0006] In order to achieve the above technical goals, the following technical solutions are adopted:

[0007] A method for preparing a thin film pressure sensor comprises the following steps:

[0008] Forming a non-completely conductive layer on one surface of the piezoresistive film layer, and forming a conductive film layer on the other surface by silk-screen printing;

[0009] Screen printing a conductive paste on the surface of the incomplete conductive layer, and performing a drying process to form at least a portion of a conductive film layer on the surface of the incomplete conductive layer;

[0010] Alternatively, a non-completely conductive layer is formed on the two opposite surfaces of the piezoresistive film layer, and a conductive paste is screen-printed on the surface of each non-completely conductive layer and dried to form at least a partial conductive film layer on the surface of each non-completely conductive layer.

[0011] In some embodiments, the incomplete conductive layer includes any one of an aluminum oxide layer, a mixed layer of aluminum oxide and zinc oxide, an anisotropic conductive adhesive film, and an anisotropic conductive coating.

[0012] In some embodiments, the aluminum oxide layer and the mixed layer are obtained by magnetron sputtering;

[0013] The anisotropic conductive adhesive film is obtained by attaching anisotropic conductive adhesive to the surface of the piezoresistive film layer;

[0014] The anisotropic conductive coating is obtained by screen printing anisotropic conductive slurry.

[0015] In some embodiments, the conductive paste contains conductive particles.

[0016] In some embodiments, the conductive paste has at least one of the following technical features:

[0017] (1) The conductive particles include at least one of silver particles, copper particles, and carbon particles;

[0018] (2) The mass content of the conductive particles is between 60% and 90%;

[0019] (3) The average particle size of the conductive particles is between 1 nm and 10 μm.

[0020] In some embodiments, the piezoresistive film layer has at least one of the following technical features:

[0021] The piezoresistive film layer contains at least one of graphene and carbon black and at least one of polypropylene, polyurethane and polyimide;

[0022] The thickness of the piezoresistive film layer is between 0.025 mm and 0.2 mm.

[0023] In some embodiments, the piezoresistive film layer has a first surface and a second surface opposite to the first surface, a first non-completely conductive layer is formed on the first surface, at least a portion of a first conductive film layer is formed on the surface of the first non-completely conductive layer; and a second conductive film layer is formed on the second surface.

[0024] In some embodiments, the positive electrode structure is stacked on the first incomplete conductive layer, the negative electrode structure is stacked on the air-avoiding region, the first conductive film layer includes a positive electrode structure and a negative electrode structure, and there is a gap between the positive electrode structure and the negative electrode structure, the positive electrode structure is stacked on the first incomplete conductive layer, and the negative electrode structure is stacked on the air-avoiding region;

[0025] or,

[0026] The first conductive film layer is a positive electrode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a negative electrode structure;

[0027] or,

[0028] The first conductive film layer is a cathode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a cathode structure.

[0029] In some embodiments, the piezoresistive film layer has a first surface and a second surface opposite to the first surface, a first non-completely conductive layer is formed on the first surface, a second non-completely conductive layer is formed on the second surface, at least a portion of a first conductive film layer is formed on the surface of the first non-completely conductive layer, and a second conductive film layer is formed on the surface of the second non-completely conductive layer.

[0030] In some embodiments, the positive electrode structure is stacked on the first incomplete conductive layer, and the negative electrode structure is stacked on the air-avoiding region. The first conductive film layer includes a positive electrode structure and a negative electrode structure, and there is a gap between the positive electrode structure and the negative electrode structure. The positive electrode structure is stacked on the first incomplete conductive layer, and the negative electrode structure is stacked on the air-avoiding region.

[0031] or,

[0032] The first conductive film layer is a positive electrode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a negative electrode structure;

[0033] or,

[0034] The first conductive film layer is a cathode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a cathode structure.

[0035] Compared with the prior art, the method for preparing a thin film pressure sensor provided in an embodiment of the present invention forms an incomplete conductive layer on at least one surface of the piezoresistive film layer, and then screen-prints a conductive layer on the incomplete conductive layer and the surface opposite to the first surface respectively. When a tunneling path exists in the piezoresistive film layer, the formed thin film pressure sensor can effectively solve the problem of piezoresistive detection failure caused by the tunneling path due to the presence of the incomplete conductive layer, and at the same time, a relatively thin film pressure sensor can be obtained.

[0036] The second object of the present invention is to provide a thin film pressure sensor. The technical solution adopted is as follows:

[0037] A thin film pressure sensor, comprising:

[0038] A piezoresistive film layer, the piezoresistive film layer having a first surface and a second surface opposite to the first surface;

[0039] A first incomplete conductive layer, wherein the first incomplete conductive layer is attached to the first surface;

[0040] a first conductive film layer, wherein the first conductive film layer is at least partially attached to the first incomplete conductive layer;

[0041] A second conductive film layer, wherein the second conductive film layer is attached to the second surface; the thin film pressure sensor is prepared according to the above-mentioned preparation method;

[0042] or,

[0043] The thin film pressure sensor comprises:

[0044] A piezoresistive film layer, the piezoresistive film layer having a first surface and a second surface opposite to the first surface;

[0045] A first incomplete conductive layer, wherein the first incomplete conductive layer is attached to the first surface;

[0046] a second incomplete conductive layer, wherein the second incomplete conductive layer is attached to the second surface;

[0047] a first conductive film layer, wherein the first conductive film layer is at least partially attached to the first incomplete conductive layer;

[0048] A second conductive film layer, wherein the second conductive film layer is attached to the second incomplete conductive layer;

[0049] The thin film pressure sensor is prepared according to the above-mentioned preparation method.

[0050] Compared with the prior art, the thin film pressure sensor provided in the embodiment of the present invention is prepared according to the above-mentioned preparation method. Therefore, the thin film pressure sensor has a smaller layer structure, is light and thin, and effectively solves the tunneling path effect existing in the piezoresistive film layer. Therefore, it has good piezoresistive detection performance, good flexibility and high bending performance.

Brief Description of the Drawings

[0051] Figure 1 A schematic diagram of the tunneling path phenomenon in the existing thin film pressure sensor;

[0052] Figure 2 A schematic diagram of a thin film pressure sensor provided by an embodiment of the present invention to prevent tunneling path phenomenon;

[0053] Figure 3 A simplified schematic diagram of a method for preparing a thin film pressure sensor provided in one embodiment of the present invention;

[0054] Figure 4 A schematic cross-sectional view of a thin film pressure sensor prepared by the method for preparing a thin film pressure sensor provided in Embodiment 1, Embodiment 4, and Embodiment 7 of the present invention;

[0055] Figure 5 A schematic cross-sectional view of a thin film pressure sensor prepared by the method for preparing a thin film pressure sensor provided in Embodiment 3 and Embodiment 6 of the present invention;

[0056] Figure 6 A schematic diagram of the three-dimensional structure of a thin film pressure sensor prepared by the method for preparing a thin film pressure sensor provided in Embodiment 3, Embodiment 6 and Embodiment 9 of the present invention;

[0057] Figure 7 A simplified schematic diagram of the process flow of the thin film pressure sensor manufacturing method provided in Embodiment 2, Embodiment 5, Embodiment 7 and Embodiment 9 of the present invention;

[0058] Figure 8 A schematic cross-sectional view of a thin film pressure sensor prepared by the method for preparing a thin film pressure sensor provided in Embodiment 2, Embodiment 5, and Embodiment 8 of the present invention;

[0059] Fig. 9 A schematic cross-sectional view of a thin film pressure sensor prepared by the method for preparing a thin film pressure sensor provided in Example 9 of the present invention;

[0060] Fig.10 Schematic diagram of detection sampling points of the thin film pressure sensor provided in Example 1.

[0061] The above-mentioned Figure 4 , Attachment Figure 5 , Attachment Figure 8 , Attachment Fig. 9 The arrows in the analog circuit indicate the direction of current flow during piezoresistive detection.

[0062] Reference numerals:

[0063] 10. Thin film pressure sensor;

[0064] 11. piezoresistive film layer; 1101. first surface; 1102. second surface;

[0065] 12. Incomplete conductive layer; 121. First incomplete conductive layer; 122. Second incomplete conductive layer;

[0066] 13. first conductive film layer; 131. positive electrode structure; 132. negative electrode structure; 133. positive electrode lead-out portion; 134. negative electrode lead-out portion;

[0067] 14. Second conductive film layer. [Specific implementation method]

[0068] The present invention is further described below in conjunction with the accompanying drawings and implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0070] Glossary:

[0071] The non-completely conductive layer refers to a film layer formed on the surface of the piezoresistive film layer. Due to the existence of this film layer, even if a tunneling path appears in the piezoresistive film layer, when a conductive film layer is formed on this film layer, this film layer can effectively block the direct conduction between the tunneling path and the conductive film layer without squeezing the piezoresistive film layer.

[0072] See also Figures 2 to 6 as well as Figures 7 to 9 , a method for preparing a thin film pressure sensor 10 provided in an embodiment of the present invention. In one embodiment, the method comprises the following steps:

[0073] Step S11 , forming a non-completely conductive layer 12 on a surface of the piezoresistive film layer 11 .

[0074] Step S12 , screen-printing a conductive film layer on the other surface of the piezoresistive film layer 11 , screen-printing a conductive paste on the surface of the incomplete conductive layer 12 , and performing a drying process to form a conductive film layer on the surface of the incomplete conductive layer 12 .

[0075] In some embodiments of step S11, the piezoresistive film layer 11 has a first surface 1101 and a second surface 1102, and the first surface 1101 and the second surface 1102 are opposite to each other, and an incomplete conductive layer 12 can be formed on the first surface 1101 or on the second surface 1102. The incomplete conductive layer 12 can be obtained by magnetron sputtering an electrical insulating material such as aluminum oxide (Al2O3), or by magnetron sputtering an electrical insulating material and a semiconductor material, for example, simultaneously magnetron sputtering Al2O3 and zinc oxide (ZnO), etc., with a magnetron sputtering power of 30W to 50W, a magnetron sputtering time of 0.5min to 2min, and a magnetron sputtering speed of 0.05nm / s to 0.09nm / s. In some embodiments, the non-completely conductive layer 12 can also be obtained by attaching anisotropic conductive film (Anisotropic Conductive Film; ACF) on the first surface 1101 or coating anisotropic conductive ink to form anisotropic conductive coating. In some embodiments, the anisotropic conductive ink contains anisotropic conductive particles, the anisotropic conductive particles have a core-shell structure, and the core part is a resin, such as at least one of polystyrene (PS), polycarbonate (PC), and high-density polyethylene resin (HDPE), and the shell part is at least one of a gold layer, a nickel layer, a silver layer, and a copper layer. Gold, nickel, silver, and copper are plated on the surface of the resin by electroplating. In some embodiments, the particle size of the anisotropic conductive particles is between 3μm and 5μm. In some embodiments, the anisotropic conductive particles are purchased from at least one conductive gold ball (Conductive Particle) of the model MCC-04IT-013C, MCC-04IT-003C, MCC-05CP-053C, MCC-05SE-053C, MCC-05SK-023C, and MCC-05SK-003C produced by Weifeng Technology Co., Ltd. In some embodiments, the thickness of the non-completely conductive layer 12 obtained by magnetron sputtering is between 10nm and 60nm, and the thickness of the non-completely conductive layer 12 obtained by attaching ACF or coating anisotropic conductive ink to form anisotropic conductive coating is between 100nm and 10μm. If the thickness is too thin, a non-completely conductive layer structure cannot be formed. If the thickness is too thick, it is completely insulated and the film layer is brittle and has no flexibility, and the function of conducting under external pressure cannot be achieved.

[0076] In some embodiments, the non-completely conductive layer 12 is patterned and attached to the first surface 1101 so that a portion of the first surface 1101 is exposed to form an air-avoiding area. These patterned non-completely conductive layers 12 are conducive to forming a positive electrode structure on the non-completely conductive layer 12 and a negative electrode structure in the air-avoiding area when the conductive paste is subsequently screen-printed on the non-completely conductive layer 12, so that the positive electrode structure and the negative electrode structure can be obtained on the same side, making the obtained thin film pressure sensor 10 lighter and thinner. Of course, the negative electrode structure can also be formed on the surface of the non-completely conductive layer 12, and the positive electrode structure can be formed in the air-avoiding area.

[0077] In some embodiments of step S12, the conductive paste is screen-printed on the incomplete conductive layer 12 and the second surface 1102. A layer of conductive paste may be screen-printed on the surface of the incomplete conductive layer 12 first, and after drying to obtain a conductive film layer, a layer of conductive paste may be screen-printed on the second surface 1102, and finally dried to obtain a conductive film layer attached to the second surface 1102. Of course, the reverse may also be true, and the formation of the two conductive film layers is not limited in order.

[0078] In some embodiments, the conductive paste contains conductive particles. The presence of the conductive particles allows the conductive particles remaining after the conductive paste is dried to form a conductive film layer.

[0079] In some embodiments, the particle size of the conductive particles is nanometer-scale, so as to facilitate obtaining a thinner conductive film layer. In some embodiments, the average particle size of the conductive particles is between 1 nm and 500 nm.

[0080] In some embodiments, the conductive particles include at least one of silver particles, copper particles, and carbon particles, such as the conductive paste contains silver particles, or the conductive paste contains copper particles, or the conductive paste contains carbon particles, or the conductive paste contains both silver particles and copper particles, or the conductive paste contains both silver particles and carbon particles, or the conductive paste contains both copper particles and carbon particles, or the conductive paste contains both silver particles, copper particles, and carbon particles.

[0081] In some embodiments, the mass content of the conductive particles in the conductive paste is between 60% and 90%. If the content of the conductive particles is too little, it is difficult to form a continuous conductive film layer, while if the content of the conductive particles is too much, it is not conducive to coating to form a uniform conductive film layer.

[0082] In some embodiments, the drying temperature is 80°C to 300°C, and the drying time is 30 min to 180 min. In some embodiments, the thickness of the conductive film layer is between 1 μm and 5 μm. If the thickness of the conductive film layer is too thin, it is difficult to form a completely conductive layer, and if the conductive film layer is too thick, it is not conducive to obtaining a thin and light thin film pressure sensor, and the flexibility and bending performance of the thin film pressure sensor will be deteriorated.

[0083] The thin film pressure sensor 10 prepared according to steps S11 to S12 forms a non-completely conductive layer 12 only on one surface of the piezoresistive film layer 11. Therefore, in some embodiments, the conductive film layer screen-printed on the surface of the non-completely conductive layer 12 is the first conductive film layer 13, and the conductive film layer screen-printed on the second surface 1102 is the second conductive film layer 14. At this time, the first conductive film layer 13 can be used as a positive electrode structure 131 or a negative electrode structure 132. When the first conductive film layer 13 is used as the positive electrode structure 131, the second conductive film layer 14 is used as the negative electrode structure 132; and when the first conductive film layer 13 is used as the negative electrode structure 132, the second conductive film layer 14 is used as the positive electrode structure 131. In some embodiments, the first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132. A part of the first conductive film layer 13 is directly screen-printed on the first surface 1101, and the remaining part is directly screen-printed on the non-complete conductive layer 12. The part screen-printed on the first surface 1101 constitutes the negative electrode structure 132, and the part screen-printed on the non-complete conductive layer 12 constitutes the positive electrode structure 131, or the part screen-printed on the first surface 1101 constitutes the positive electrode structure 131, and the part screen-printed on the non-complete conductive layer 12 constitutes the negative electrode structure 132, and the second conductive film layer 14 serves as only one conductive layer. In some embodiments, the positive electrode structure and the negative electrode structure on the same side of the piezoresistive film layer 11 are distributed in a forked finger shape.

[0084] In another embodiment, the preparation method comprises the following steps:

[0085] Step S21 , forming a non-completely conductive layer 12 on two opposite surfaces of the piezoresistive film layer 11 .

[0086] Step S22 , screen-printing a conductive paste on the surface of each incomplete conductive layer 12 , and performing a drying process to form a conductive film layer on the surface of each incomplete conductive layer 12 .

[0087] In some embodiments of step S21, the piezoresistive film layer 11 has a first surface 1101 and a second surface 1102, and the first surface 1101 and the second surface 1102 are opposite to each other, a first incomplete conductive layer 121 is formed on the first surface 1101, and a second incomplete conductive layer 122 is formed on the second surface 1102. The first incomplete conductive layer 121 and the second incomplete conductive layer 122 can be obtained by magnetron sputtering an electrical insulating material such as aluminum oxide (Al2O3), or by magnetron sputtering an electrical insulating material and a semiconductor material, for example, simultaneously magnetron sputtering Al2O3 and zinc oxide (ZnO), etc., the magnetron sputtering speed is between 0.05nm / s and 0.09nm / s, the magnetron sputtering power is 30W to 50W, and the magnetron sputtering time is 0.5min to 2min.

[0088] In some embodiments, the first incomplete conductive layer 121 or the second incomplete conductive layer 122 may also be obtained by attaching an anisotropic conductive film to the first surface 1101 or coating anisotropic conductive ink.

[0089] In some embodiments, the thickness of the first non-completely conductive layer 1201 obtained by magnetron sputtering is between 10nm and 60nm, and the thickness of the first non-completely conductive layer 1201 obtained by attaching ACF or coating anisotropic conductive ink to form an anisotropic conductive coating is between 100nm and 10μm. If the thickness is too thin, a non-completely conductive layer structure cannot be formed. If the thickness is too thick, it is completely insulated and the film layer is brittle and not flexible, and the function of conduction under external pressure cannot be achieved.

[0090] In some embodiments, the thickness of the second non-completely conductive layer 1202 obtained by magnetron sputtering is between 10nm and 60nm, and the thickness of the second non-completely conductive layer 1202 obtained by attaching ACF or coating anisotropic conductive ink to form an anisotropic conductive coating is between 100nm and 10μm. If the thickness is too thin, the non-completely conductive layer structure cannot be formed. If the thickness is too thick, it is completely insulated and the film layer is brittle and not flexible, and the function of conduction under external pressure cannot be achieved.

[0091] In some embodiments, the first non-complete conductive layer 1201 is patterned and attached to the first surface 1101 so that the first surface 1101 is partially exposed to form an air-avoiding area. These patterned first non-complete conductive layers 1201 are conducive to forming a positive electrode structure on the surface of the first non-complete conductive layer 1201 and a negative electrode structure in the air-avoiding area when the conductive paste is subsequently screen-printed on the first non-complete conductive layer 1201, or forming a negative electrode structure on the surface of the first non-complete conductive layer 1201 and a positive electrode structure in the air-avoiding area, so that the positive electrode structure and the negative electrode structure can be obtained on the same side, making the obtained thin film pressure sensor 10 lighter and thinner. In some embodiments, the positive electrode structure and the negative electrode structure on the same side of the piezoresistive film layer 11 are distributed in a forked finger shape.

[0092] In some embodiments of step S22, a layer of conductive paste may be screen-printed on the surface of the first incomplete conductive layer 121, and dried to obtain a conductive film layer attached to the first incomplete conductive layer 121, and then a layer of conductive paste may be screen-printed on the surface of the second incomplete conductive layer 122, and finally dried to obtain a conductive film layer attached to the second surface 1102. Of course, the reverse may also be true, and there is no order in which the two conductive film layers are formed. In some embodiments, the conductive paste contains conductive particles, and the presence of the conductive particles allows the conductive particles left after the conductive paste is dried to form a conductive film layer.

[0093] In some embodiments, the particle size of the conductive particles is nanometer-scale, so as to facilitate obtaining a thinner conductive film layer.

[0094] In some embodiments, the conductive particles include at least one of silver particles, copper particles, and carbon particles, such as the conductive paste contains silver particles, or the conductive paste contains copper particles, or the conductive paste contains carbon particles, or the conductive paste contains both silver particles and copper particles, or the conductive paste contains both silver particles and carbon particles, or the conductive paste contains both copper particles and carbon particles, or the conductive paste contains both silver particles, copper particles, and carbon particles.

[0095] In some embodiments, the mass content of the conductive particles in the conductive paste is between 60% and 90%. If the content of the conductive particles is too little, it is difficult to form a continuous conductive film layer, while if the content of the conductive particles is too much, it is not conducive to coating to form a uniform conductive film layer.

[0096] In some embodiments, the drying temperature is 80° C. to 300° C., and the drying time is 30 min to 180 min.

[0097] The thin film pressure sensor 10 prepared according to steps S21 to S22 has an incomplete conductive layer 12 formed on two opposite surfaces of the piezoresistive film layer 11. Therefore, in some embodiments, the incomplete conductive layer 12 formed on the first surface 1101 is the first incomplete conductive layer 121, and the conductive film layer screen-printed on the surface of the first incomplete conductive layer 121 is the first conductive film layer 13. The incomplete conductive layer 12 formed on the second surface 1102 is the second incomplete conductive layer 122, and the conductive film layer screen-printed on the second incomplete conductive layer 122 is the second conductive film layer 14. At this time, the first conductive film layer 13 can be used as a positive electrode structure 131 or a negative electrode structure 132. When the first conductive film layer 13 is used as the positive electrode structure 131, the second conductive film layer 14 is used as the negative electrode structure 132; and when the first conductive film layer 13 is used as the negative electrode structure 132, the second conductive film layer 14 is used as the positive electrode structure 131. In some embodiments, the first non-complete conductive layer 121 is patterned and attached to the first surface 1101 so that the first surface 1101 is partially exposed to form an air-avoiding area. The patterned first non-complete conductive layer 121 is conducive to forming a positive electrode structure on the surface of the first non-complete conductive layer 121 and a negative electrode structure in the air-avoiding area when screen-printing the conductive paste, or forming a negative electrode structure on the surface of the first non-complete conductive layer 121 and a positive electrode structure in the air-avoiding area.

[0098] In some embodiments, the first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132, and the second conductive film layer 14 serves as a conductive layer. At this time, the first conductive film layer 13 is patterned, and the positive electrode structure 131 and the negative electrode structure 132 can both constitute a finger-shaped electrode. Of course, other patterned structures can also be used.

[0099] In the above two preparation embodiments, the piezoresistive film layer 11 may include a composite film of polyurethane (PU), polyimide (PI), polypropylene (PP) and graphene (or carbon black), and the composite film is a piezoresistive film layer 11 formed by mixing polypropylene and graphene (or carbon black) with each other or doping graphene (or carbon black) in polypropylene. Mixing graphene (or carbon black) in polypropylene can help improve the piezoresistive performance. In addition, it can also be a composite film of PI and graphene (or carbon black), or a composite film of PU and graphene (or carbon black). In some embodiments, the thickness of the composite film is between 0.025 mm and 0.2 mm, which is conducive to the thinness of the thin film pressure sensor 10.

[0100] See also Figure 5 , Figure 7 The thin film pressure sensor 10 prepared by the above two implementation modes has the following three structures.

[0101] The structure of the first thin film pressure sensor 10 is as follows: a non-completely conductive layer 12 is stacked on one surface of the piezoresistive film layer 11 , a second conductive film layer 14 is screen-printed on the other surface, and a first conductive film layer 13 is screen-printed on the surface of the non-completely conductive layer 12 .

[0102] See also Figure 4 , Figure 5 The basic working process of the first thin film pressure sensor 10 is as follows:

[0103] When squeezed, the first conductive film layer 13 and the piezoresistive film layer 11 change from incomplete contact to complete contact, and the incomplete contact area is squeezed. At this time, the first conductive film layer 13 and the piezoresistive film layer 11 are connected, and the current flows from the positive lead 133 into the first conductive film layer 13, and crosses the piezoresistive film layer 11 to the second conductive film layer 14, and flows out through the negative lead 134. When the positive lead 133 and the negative lead 134 are connected, the change in current can be detected to obtain pressure sensing information. When there is no pressure, the first conductive film layer 13 and the piezoresistive film layer 11 are in an incomplete contact state, that is, the first conductive film layer 13 and the piezoresistive film layer 11 are not connected to the piezoresistive film layer 11 due to the incomplete conductive layer 12.

[0104] The structure of the second thin film pressure sensor 10 is as follows: a non-completely conductive layer 12 (i.e., a first non-completely conductive layer 121 and a second non-completely conductive layer 122) is stacked on two opposite surfaces of the piezoresistive film layer 11, and a conductive film layer is screen-printed on the surface of each non-completely conductive layer 12 (i.e., a first conductive film layer 13 is screen-printed on the surface of the first non-completely conductive layer 121, and a second conductive film layer 14 is screen-printed on the surface of the second non-completely conductive layer 122). The basic working process of the second thin film pressure sensor 10 is the same as the basic working process principle of the first thin film pressure sensor 10, and will not be elaborated here to save space.

[0105] See also Figure 6 , Figure 7 The structure of the third thin film pressure sensor 10 is as follows: a non-completely conductive layer 12 is stacked on one surface of the piezoresistive film layer 11, and a second conductive film layer 14 is screen-printed on the other surface. The non-completely conductive layer 12 is patterned so that a partial surface of the piezoresistive film layer 11 is exposed to form a hollow area. The surface of the non-completely conductive layer 12 and the hollow area are screen-printed with a first conductive film layer 13. The first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132. The positive electrode structure 131 is stacked on the non-completely conductive layer 12, and the negative electrode structure is stacked on the hollow area. The positive electrode structure 131 and the negative electrode structure 132 are located on the same layer, and the end of the positive electrode structure 131 has a positive electrode lead-out portion 133, and the end of the negative electrode structure 132 has a negative electrode lead-out portion 134.

[0106] See also Figure 7 The basic working process of the third thin film pressure sensor 10 is as follows:

[0107] When squeezed, the positive electrode structure 131 and the piezoresistive film layer 11 change from incomplete contact to complete contact. At this time, the positive electrode structure 131 and the piezoresistive film layer 11 are conductive, and the current enters the positive electrode structure 131 from the positive electrode lead-out portion 133, flows along the positive electrode structure 131 to the piezoresistive film layer 11, and crosses the piezoresistive film layer 11 to the second conductive film layer 14, and then flows along the second conductive film layer 14, and flows through the part where the negative electrode structure 132 and the piezoresistive film layer 11 are in complete contact. The current crosses the piezoresistive film layer 11 and enters the negative electrode structure 132. When the positive electrode lead-out portion 133 and the negative electrode lead-out portion 134 are connected, the change in current can be detected to obtain pressure sensing information. When there is no pressure, the positive electrode structure 131 and the piezoresistive film layer 11 are in an incomplete contact state, the positive electrode structure 131 and the piezoresistive film layer 11 are not conductive, and the negative electrode structure 132 and the piezoresistive film layer 11 can be conductive or not conductive.

[0108] The thin film pressure sensor 10 prepared by the method for preparing the thin film pressure sensor 10 provided in the embodiment of the present invention can be used as a pressure-sensitive film sensor, a robot component (such as robot skin), a component of an electronic device, and the like.

[0109] In some embodiments, the robot includes skin, which includes the thin film pressure sensor 10 prepared according to the embodiment of the present invention, that is, the robot skin. The electronic device includes a thin film circuit, which includes the thin film pressure sensor 10 prepared according to the embodiment of the present invention.

[0110] In order to better illustrate the technical solution of the present invention, a further description is given below through multiple embodiments.

[0111] Example 1

[0112] See also Figure 3 , Figure 4 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0113] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PP as the substrate and graphene doping, and has a thickness of 0.1 mm.

[0114] (2) A non-completely conductive layer 12 is magnetron sputtered on the first surface 1101 of the piezoresistive film layer 11. The target material of the magnetron sputtering is aluminum oxide (Al2O3), the sputtering power is 35 W, the sputtering speed is 0.07 nm / s, the sputtering time is 1 min, and the average thickness of the obtained non-completely conductive layer 12 is 15 nm.

[0115] (3) Screen-printing a conductive paste on the second surface 1102 of the piezoresistive film layer 11, wherein the conductive paste contains silver particles, and the mass content of the silver particles in the conductive paste is 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100°C for 60 minutes to obtain a combination of the piezoresistive film layer 11 and the second conductive film layer 14, wherein the thickness of the second conductive film layer 14 is 3 μm.

[0116] (4) Screen-printing a conductive paste on the surface of the non-completely conductive layer 12 obtained in step (2), wherein the conductive paste contains silver particles, and the mass content of the silver particles in the conductive paste is 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 140° C. for 30 min to obtain a first conductive film layer 13. The thickness of the first conductive film layer 13 is 3 μm.

[0117] The obtained thin film pressure sensor is used to detect the resistance value under pressure. Specifically, a 2 cm × 2 cm detection area is randomly demarcated (for example, Fig.10 Then, four points are evenly selected in the detection area, such as the midpoints along the AO line, the BO line, the CO line and the DO line (points E, F, G, and H), and a pressure gauge is used to press at different pressures to detect the resistance. Each point is detected three times and the average value is taken. The results are shown in Table 1.

[0118] Table 1 Summary of resistance value test results (unit: kΩ)

[0119]

[0120] It can be seen from Table 1 that points E, F, G, and H all have a large resistance under a pressure of 20g. As the pressure value increases, the resistance of each point gradually decreases until the resistance value of points E and H drops below 1kΩ under a pressure of 1500g, while the resistance value of points F and G is still above 1kΩ, indicating that in the obtained thin film pressure sensor, the barrier effect of the non-completely conductive layer 12 is better and it is not easy to produce a tunneling effect.

[0121] Example 2

[0122] See also Figure 7 , Figure 8 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0123] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is PU with a thickness of 0.1 mm.

[0124] (2) A non-completely conductive layer 12 is magnetron sputtered on the first surface 1101 and the second surface 1102 of the piezoresistive film layer 11, respectively. The target material of the magnetron sputtering is Al2O3, the sputtering power is 35 W, the sputtering speed is 0.07 nm / s, the sputtering time is 1.5 min, and the average thickness of the obtained non-completely conductive layer 12 is 20 nm.

[0125] (3) Conductive paste is screen-printed on the surfaces of the two non-completely conductive layers 12, respectively. The conductive paste contains silver particles, and the mass content of the silver particles is 80%. The piezoresistive film layer 11 printed with the conductive paste is then placed in a blast oven and dried at 100° C. for 60 min to obtain a first conductive film layer 13 and a second conductive film layer 14. The first conductive film layer 13 is a positive electrode structure 131 with a thickness of 3 μm, and the second conductive film layer 14 is a negative electrode structure 132 with a thickness of 3 μm.

[0126] The resistance value was tested by referring to the method of Example 1, and the results are shown in Table 2.

[0127] Table 2 Summary of resistance value test results (unit: kΩ)

[0128]

[0129] It can be seen from Table 2 that points E, F, G, and H all have a large resistance under a pressure of 20g. As the pressure value increases, the resistance of each point gradually decreases until the resistance value of each point drops below 1kΩ under a pressure of 600g. This indicates that in the obtained thin film pressure sensor, the barrier effect of the non-completely conductive layer 12 is better and it is not easy to produce a tunneling effect.

[0130] Example 3

[0131] See also Figure 3 , Figure 5 , Figure 6 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0132] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is PU with a thickness of 0.1 mm.

[0133] (2) A non-completely conductive layer 12 is magnetron sputtered on the first surface 1101 of the piezoresistive film layer 11. The target material of the magnetron sputtering is aluminum oxide (Al2O3), the sputtering power is 35 W, the sputtering speed is 0.07 nm / s, and the sputtering time is 0.8 min. The average thickness of the obtained non-completely conductive layer 12 is 10 nm. The non-completely conductive layer 12 is patterned so that a part of the first surface 1101 is exposed to form a void area (not shown in the figure).

[0134] (3) A conductive paste is screen-printed on the surface of the non-completely conductive layer 12 and the air-avoiding area of ​​the first surface 1101, respectively. The conductive paste contains silver particles, and the mass content of the silver particles is 80%. The piezoresistive film layer 11 printed with the conductive paste is then placed in a blast oven and dried at 200°C for 30 minutes to obtain a first conductive film layer 13. The first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132. The negative electrode structure 132 is screen-printed in the air-avoiding area, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132. The average thickness of the positive electrode structure 131 is 1.5 μm, and the average thickness of the negative electrode structure 132 is 1.49 μm.

[0135] (4) Screen-printing a conductive paste on the second surface 1102, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 200° C. for 30 minutes to obtain a second conductive film layer 14. The thickness of the second conductive film layer 14 is 2 μm.

[0136] The resistance value was tested by referring to the method of Example 1, and the results are shown in Table 3.

[0137] Table 3 Summary of resistance value test results (unit: kΩ)

[0138]

[0139] It can be seen from Table 3 that points E, F, G, and H all have a large resistance under a pressure of 20g. As the pressure value increases, the resistance of each point gradually decreases until the resistance value of each point drops below 1kΩ under a pressure of 1500g. This indicates that in the obtained thin film pressure sensor, the barrier effect of the non-completely conductive layer 12 is better and it is not easy to produce a tunneling effect.

[0140] Example 4

[0141] See also Figure 3 , Figure 4 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0142] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0143] (2) ACF glue is pressed onto the first surface 1101 of the piezoresistive film layer 11. Specifically, the ACF glue is pressed onto the first surface 1101 of the piezoresistive film layer 11 at 90° C. and a pressure of 2 MPa to obtain a non-completely conductive layer 12. The average thickness of the non-completely conductive layer 12 is 1 μm.

[0144] (3) Screen-printing a conductive paste on the second surface 1102 of the piezoresistive film layer 11, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100° C. for 60 min to obtain a combination of the piezoresistive film layer 11 and the second conductive film layer 14, wherein the average thickness of the second conductive film layer 14 is 3 μm.

[0145] (4) Screen-printing a conductive paste on the surface of the non-completely conductive layer 12 obtained in step (2), wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, placing the piezoresistive film layer 11 printed with the conductive paste in a blast oven and drying it at 140° C. for 30 min to obtain a first conductive film layer 13, wherein the average thickness of the first conductive film layer 13 is 3 μm.

[0146] Example 5

[0147] See also Figure 7 , Figure 8 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0148] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0149] (2) ACF glue is pressed onto the first surface 1101 and the second surface 1102 of the piezoresistive film layer 11 respectively. Specifically, the ACF glue is pressed onto the first surface 1101 and the second surface 1102 of the piezoresistive film layer 11 at 90°C and a pressure of 2MPa to obtain two layers of incomplete conductive layers 12, namely, a first incomplete conductive layer 121 attached to the first surface 1101 with an average thickness of 200nm, and a second incomplete conductive layer 122 attached to the second surface 1102 with an average thickness of 200nm.

[0150] (3) Screen-printing a conductive paste on the first non-completely conductive layer 121, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100° C. for 60 minutes to obtain a first conductive film layer 13 with an average thickness of 3 μm.

[0151] (4) Screen-printing a conductive paste on the surface of the second non-completely conductive layer 122 obtained in step (2), wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, placing the piezoresistive film layer 11 printed with the conductive paste in a blast oven and drying it at 140° C. for 30 min to obtain a second conductive film layer 14 with an average thickness of 3 μm.

[0152] Example 6

[0153] See also Figure 3 , Figure 5 as well as Figure 6 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0154] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0155] (2) ACF glue is pressed onto the first surface 1101 of the piezoresistive film layer 11. Specifically, the ACF glue is pressed onto the first surface 1101 of the piezoresistive film layer 11 at 90°C and a pressure of 2MPa to obtain a non-completely conductive layer 12 with an average thickness of 600nm. The non-completely conductive layer 12 is patterned so that a portion of the first surface 1101 is exposed to form an air avoidance area (not shown in the figure).

[0156] (3) Screen-printing a conductive paste on the second surface 1102 of the piezoresistive film layer 11, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100° C. for 60 minutes to obtain a second conductive film layer 14 with a thickness of 2 μm.

[0157] (4) Screen-printing a conductive paste on the surface of the non-completely conductive layer 12 obtained in step (2) and the air-avoiding area, respectively, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 140° C. for 30 min to obtain a first conductive film layer 13. The first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132. The positive electrode structure 131 is screen-printed on the surface of the non-completely conductive layer 12, while the negative electrode structure 132 is screen-printed on the air-avoiding area. The average thickness of the positive electrode structure 131 is 2 μm, and the average thickness of the negative electrode structure 132 is 1.94 μm.

[0158] Example 7

[0159] See also Figure 3 , Figure 4 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0160] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0161] (2) Anisotropic conductive ink is screen-printed on the first surface 1101 of the piezoresistive film layer 11, wherein the anisotropic conductive ink contains anisotropic conductive particles selected from MCC-04IT-003C, and then baked at 100°C for 30 minutes to obtain a non-completely conductive layer 12 with an average thickness of 500 nm.

[0162] (3) Screen-printing a conductive paste on the second surface 1102 of the piezoresistive film layer 11, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100° C. for 60 min to obtain a combination of the piezoresistive film layer 11 and the second conductive film layer 14, wherein the average thickness of the second conductive film layer 14 is 5 μm.

[0163] (4) Screen-printing a conductive paste on the surface of the non-completely conductive layer 12 obtained in step (2), wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, placing the piezoresistive film layer 11 printed with the conductive paste in a blast oven and drying it at 140° C. for 30 min to obtain a first conductive film layer 13 with an average thickness of 3 μm.

[0164] Example 8

[0165] See also Figure 7 , Figure 8 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0166] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0167] (2) Anisotropic conductive ink is screen-printed on the first surface 1101 and the second surface 1102 of the piezoresistive film layer 11, respectively. The anisotropic conductive ink contains anisotropic conductive particles. The mass content of the anisotropic conductive particles is 70%. The anisotropic conductive particles are selected from MCC-04IT-003C. Then, the piezoresistive film layer 11 is baked at 100°C for 30 minutes to obtain two layers of incomplete conductive layers 12, namely, a first incomplete conductive layer 121 attached to the first surface 1101, with an average thickness of 250nm, and a second incomplete conductive layer 122 attached to the second surface 1102, with an average thickness of 250nm.

[0168] (3) Screen-printing a conductive paste on the first non-completely conductive layer 121, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100° C. for 60 minutes to obtain a first conductive film layer 13 with an average thickness of 2.5 μm.

[0169] (4) Screen-printing a conductive paste on the surface of the second non-completely conductive layer 122 obtained in step (2), wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 140° C. for 30 min to obtain a second conductive film layer 14 with an average thickness of 2.5 μm.

[0170] Example 9

[0171] See also Figure 7 , Fig. 9 , Figure 6 , a method for preparing a thin film pressure sensor 10, comprising the following steps:

[0172] (1) Clean the piezoresistive film layer 11 to remove oil stains and impurities on the surface of the piezoresistive film layer 11; wherein the piezoresistive film layer 11 is a composite film with PI as the substrate and carbon black doping, and has a thickness of 0.1 mm.

[0173] (2) Anisotropic conductive ink is respectively screen-printed on the first surface 1101 and the second surface 1102 of the piezoresistive film layer 11, wherein the anisotropic conductive ink contains anisotropic conductive particles, the mass content of the anisotropic conductive particles is 80%, and the anisotropic conductive particles are selected from MCC-04IT-003C. The piezoresistive film layer 11 is then baked at 100°C for 30 minutes to obtain two layers of incomplete conductive layers 12, namely, a first incomplete conductive layer 121 attached to the first surface 1101, with an average thickness of 300 nm, the first incomplete conductive layer 1201 having an air avoidance area so that the first surface 1101 is partially exposed, and a second incomplete conductive layer 1202 attached to the second surface 1102, with an average thickness of 300 nm.

[0174] (3) Screen-printing a conductive paste on the surface of the first non-complete contact layer 1201 and the air-avoiding area, respectively, wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, the piezoresistive film layer 11 printed with the conductive paste is placed in a blast oven and dried at 100°C for 60 minutes to obtain a first conductive film layer 13 with a thickness of 2 μm. The first conductive film layer 13 includes a positive electrode structure 131 and a negative electrode structure 132, and there is a gap between the positive electrode structure 131 and the negative electrode structure 132. The positive electrode structure 131 is screen-printed on the first non-complete conductive layer 1201 with an average thickness of 2 μm, and the negative electrode structure 132 is screen-printed in the air-avoiding area with an average thickness of 1.97 μm.

[0175] (4) Screen-printing a conductive paste on the surface of the second non-completely conductive layer 1202 obtained in step (2), wherein the conductive paste contains silver particles with a mass content of 80%. Subsequently, placing the piezoresistive film layer 11 printed with the conductive paste in a blast oven and drying it at 140° C. for 30 min to obtain a second conductive film layer 14. The average thickness of the second conductive film layer 14 is 2 μm.

[0176] The above are only some embodiments of the present invention. It should be pointed out that, for those skilled in the art, improvements can be made without departing from the inventive concept of the present invention, but these all belong to the protection scope of the present invention.

Claims

1. A method for preparing a thin film pressure sensor, characterized in that: The following steps are involved: Forming a non-completely conductive layer on one surface of the piezoresistive film layer, and forming a conductive film layer on the other surface by silk-screen printing; Screen printing a conductive paste on the surface of the incomplete conductive layer, and performing a drying process to form at least a portion of a conductive film layer on the surface of the incomplete conductive layer; Alternatively, a non-completely conductive layer is formed on two opposite surfaces of the piezoresistive film layer, and a conductive paste is screen-printed on the surface of each non-completely conductive layer, and dried to form at least a portion of a conductive film layer on the surface of each non-completely conductive layer; The incomplete conductive layer includes any one of an aluminum oxide layer, a mixed layer of aluminum oxide and zinc oxide, an anisotropic conductive adhesive film, and an anisotropic conductive coating; The aluminum oxide layer and the mixed layer are obtained by magnetron sputtering; the anisotropic conductive adhesive film is obtained by attaching anisotropic conductive adhesive to the surface of the piezoresistive film layer; and the anisotropic conductive coating is obtained by screen printing anisotropic conductive slurry.

2. The method for preparing a thin film pressure sensor according to claim 1, characterized in that: The conductive paste contains conductive particles.

3. The method for preparing a thin film pressure sensor according to claim 2, characterized in that: The conductive paste has at least one of the following technical features: (1) The conductive particles include at least one of silver particles, copper particles, and carbon particles; (2) The mass content of the conductive particles is between 60% and 90%; (3) The average particle size of the conductive particles is between 1 nm and 10 μm.

4. The method for preparing a thin film pressure sensor according to claim 1, characterized in that: The piezoresistive film layer has at least one of the following technical features: The piezoresistive film layer contains at least one of graphene and carbon black and at least one of polypropylene, polyurethane and polyimide; The thickness of the piezoresistive film layer is between 0.025 mm and 0.2 mm.

5. The method for preparing a thin film pressure sensor according to any one of claims 1 to 4, characterized in that: The piezoresistive film layer has a first surface and a second surface opposite to the first surface, a first incomplete conductive layer is formed on the first surface, at least a part of a first conductive film layer is formed on the surface of the first incomplete conductive layer; and a second conductive film layer is formed on the second surface.

6. The method for preparing a thin film pressure sensor according to claim 5, characterized in that: The first incomplete conductive layer is patterned so that the first surface is partially exposed to form an air-avoiding area, the first conductive film layer includes a positive electrode structure and a negative electrode structure, and there is a gap between the positive electrode structure and the negative electrode structure, the positive electrode structure is stacked on the first incomplete conductive layer, and the negative electrode structure is stacked on the air-avoiding area; or, The first conductive film layer is a positive electrode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a negative electrode structure; or, The first conductive film layer is a cathode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a cathode structure.

7. The method for preparing a thin film pressure sensor according to any one of claims 1 to 4, characterized in that: The piezoresistive film layer has a first surface and a second surface opposite to the first surface, a first incomplete conductive layer is formed on the first surface, a second incomplete conductive layer is formed on the second surface, at least a portion of a first conductive film layer is formed on the surface of the first incomplete conductive layer, and a second conductive film layer is formed on the surface of the second incomplete conductive layer.

8. The method for preparing a thin film pressure sensor according to claim 7, characterized in that: The first incomplete conductive layer is patterned so that the first surface is partially exposed to form an air-avoiding area, the first conductive film layer includes a positive electrode structure and a negative electrode structure, and there is a gap between the positive electrode structure and the negative electrode structure, the positive electrode structure is stacked on the first incomplete conductive layer, and the negative electrode structure is stacked on the air-avoiding area; or, The first conductive film layer is a positive electrode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a negative electrode structure; or, The first conductive film layer is a cathode structure and is completely stacked on the first incomplete conductive layer, and the second conductive film layer is a cathode structure.

9. A thin film pressure sensor, characterized in that: The thin film pressure sensor comprises: A piezoresistive film layer, the piezoresistive film layer having a first surface and a second surface opposite to the first surface; A first incomplete conductive layer, wherein the first incomplete conductive layer is attached to the first surface; a first conductive film layer, wherein the first conductive film layer is at least partially attached to the first incomplete conductive layer; a second conductive film layer, wherein the second conductive film layer is attached to the second surface; the thin film pressure sensor is prepared according to the preparation method of any one of claims 5 to 6; or, The thin film pressure sensor comprises: A piezoresistive film layer, the piezoresistive film layer having a first surface and a second surface opposite to the first surface; A first incomplete conductive layer, wherein the first incomplete conductive layer is attached to the first surface; a second incomplete conductive layer, wherein the second incomplete conductive layer is attached to the second surface; a first conductive film layer, wherein the first conductive film layer is at least partially attached to the first incomplete conductive layer; A second conductive film layer, wherein the second conductive film layer is attached to the second incomplete conductive layer; The thin film pressure sensor is prepared according to the preparation method according to any one of claims 7 to 8.

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