A flexible conductive polymer film-based pressure sensor and a method for manufacturing the same

Abstract

The application discloses a pressure sensor based on a flexible conductive polymer film and a preparation method thereof. The pressure sensor comprises, from top to bottom, an upper flexible substrate layer, an upper electrode layer, a pressure-sensitive functional layer, a lower electrode layer and a lower flexible substrate layer. The pressure-sensitive functional layer comprises a plurality of flexible pressure-sensitive layers and a plurality of flexible insulating separation layers. A plurality of through holes are arranged on the flexible insulating separation layers. When the pressure-sensitive functional layer is subjected to pressure, the flexible pressure-sensitive layers are in contact with adjacent another flexible pressure-sensitive layer, the upper electrode layer or the lower electrode layer through the through holes. The pressure sensor has the advantages that the pressure-sensitive functional layer is innovatively structured, the flexible pressure-sensitive layers and the porous flexible insulating separation layers are combined to form the pressure-sensitive functional layer, the pressure sensor has the advantages of convenient initial pressure monitoring, simple structure, energy saving during long-term power monitoring, small heat generation and difficulty in damage, and the like.

Description

Technical Field

[0001] This invention belongs to the field of pressure sensor technology, specifically relating to a pressure sensor based on a flexible conductive polymer film and its fabrication method. Background Technology

[0002] Pressure sensors are key devices that convert mechanical pressure into electrical signals, and they are widely used in industries such as industry, aerospace, smart homes, smart healthcare, and smart packaging. Flexible pressure sensors, due to their deformable nature, conform to irregular surfaces and deform accordingly, and have become a cutting-edge research area in this field.

[0003] Flexible pressure sensors can generally be classified into piezoresistive, capacitive, and piezoelectric types according to their working principles. Piezoresistive flexible pressure sensors typically consist of a flexible base film, an electrode layer, a pressure-sensitive layer, and an encapsulation layer. In conventional piezoresistive flexible pressure sensors, after a voltage is applied to the electrodes, the pressure-sensitive layer, being a conductor with variable resistance that typically decreases with increasing pressure, continuously consumes electrical energy even when no pressure is applied. This results in energy waste and potential damage due to overheating caused by prolonged continuous current flow. Furthermore, traditional flexible pressure sensors with an upper and lower electrode layer sandwiching a pressure-sensitive layer rely solely on adjusting the material properties and thickness of the pressure-sensitive layer to control the measurement range and sensitivity. This limited adjustment method, flexibility, and controllability are problematic. Summary of the Invention

[0004] This invention provides a pressure sensor based on a flexible conductive polymer film and its preparation method, aiming to overcome at least to some extent the above-mentioned shortcomings of the prior art.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: The present invention provides a pressure sensor based on a flexible conductive polymer film, which includes an upper flexible substrate layer, an upper electrode layer, a pressure-sensitive functional layer, a lower electrode layer and a lower flexible substrate layer arranged sequentially from top to bottom. The pressure-sensitive functional layer includes several flexible pressure-sensitive layers and several flexible insulating separation layers. The flexible insulating separation layers are provided with a plurality of through holes at intervals. When the pressure-sensitive functional layer is subjected to pressure, the flexible pressure-sensitive layer makes contact and conduction with another adjacent flexible pressure-sensitive layer, upper electrode layer or lower electrode layer through the through holes.

[0006] Based on the above technical solution, the present invention can also make the following further specific choices or better choices.

[0007] Furthermore, the pressure-sensitive functional layer includes two flexible pressure-sensitive layers and a flexible insulating separator layer, with the flexible insulating separator layer located between the two flexible pressure-sensitive layers.

[0008] Furthermore, the pressure-sensitive functional layer includes a flexible pressure-sensitive layer and a flexible insulating separator layer, wherein the flexible insulating separator layer is located between the flexible pressure-sensitive layer and the upper electrode layer or between the flexible pressure-sensitive layer and the lower electrode layer.

[0009] Furthermore, the flexible pressure-sensitive layer and the flexible insulating separator layer are bonded and fixed together by a flexible adhesive, which is a flexible epoxy resin adhesive or an acrylic resin adhesive.

[0010] Furthermore, the flexible insulating separator layer is a PI film, PET film, or PDMS film with the through holes evenly distributed thereon, the thickness of the flexible insulating separator layer is 0.05-0.25mm, and the through holes are round holes, elliptical holes, or polygonal holes.

[0011] Furthermore, the through hole is a round hole or a square hole, with a corresponding diameter or side length of 0.5-5mm.

[0012] Furthermore, the upper flexible substrate layer and the lower flexible substrate layer are PI film, PET film or PDMS film.

[0013] Furthermore, the upper electrode layer and the lower electrode layer are metal conductive layers or conductive ink layers formed on the corresponding surfaces of the upper flexible substrate layer and the lower flexible substrate layer.

[0014] Furthermore, the flexible pressure-sensitive layer is a flexible conductive polymer film with elasticity and containing conductive fillers, and the thickness of the flexible conductive polymer film is 0.25-1mm.

[0015] In another aspect, the present invention provides a method for preparing the above-mentioned pressure sensor, which includes the following steps:

[0016] S1. A conductive layer is formed on a flexible substrate by magnetron sputtering or printing technology, and the substrate is cut to form an upper flexible substrate layer with an upper electrode layer and a lower flexible substrate layer with a lower electrode layer, for later use;

[0017] S2. Prepare several layers of flexible pressure-sensitive layer and several layers of flexible insulating separator layer, and bond the flexible pressure-sensitive layer and the flexible insulating separator layer together with flexible adhesive to form the pressure-sensitive functional layer;

[0018] S3. The upper flexible substrate layer with the upper electrode layer, the lower flexible substrate layer with the lower electrode layer, and the pressure-sensitive functional layer are bonded and fixed with flexible adhesive to obtain the pressure sensor.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The pressure sensor provided by this invention features a structural innovation in the pressure-sensitive functional layer. It employs a flexible pressure-sensitive layer and a porous flexible insulating separator layer to form the pressure-sensitive functional layer, which has significant advantages such as easy adjustment of the initial pressure to be monitored, simple structure, energy saving during long-term power-on monitoring, low heat generation, and resistance to damage.

[0021] When voltage is applied to the upper and lower sides of the pressure sensor and the pressure sensor is continuously monitored under external pressure, due to the isolation effect of the flexible insulating separator, if there is no pressure or the pressure is too small to cause the elastic flexible pressure-sensitive layer to deform and contact the conductor (flexible pressure-sensitive layer or upper and lower electrode layers) on the other side through the through hole of the flexible insulating separator, the pressure sensor basically has no current flowing through it, resulting in energy saving, low heat generation, and less damage. If the applied external pressure reaches or exceeds the minimum set pressure for monitoring, the elastic flexible pressure-sensitive layer will deform and contact the conductor on the other side through the through hole, resulting in a significant reduction in resistance. Based on the detected current or resistance change, pressure monitoring can be achieved. Subsequently, as the pressure further increases, the contact resistance decreases or the conductive filler in the flexible pressure-sensitive layer becomes tightly contacted due to compression, further reducing the resistance. That is, the pressure change is monitored by the degree of increase in current or further decrease in resistance. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of a pressure sensor based on a flexible conductive polymer film provided by the present invention, which has two flexible pressure-sensitive layers and one flexible insulating separator layer.

[0023] Figure 2 A cross-sectional schematic diagram of another pressure sensor based on a flexible conductive polymer film provided by the present invention, having a flexible pressure-sensitive layer and a flexible insulating separator layer;

[0024] Figure 3 for Figure 1 or Figure 2 A top view of the flexible insulating separator in the pressure sensor shown.

[0025] The attached diagram lists the components represented by each number as follows:

[0026] 1. Upper flexible substrate layer; 2. Upper electrode layer; 3. Pressure-sensitive functional layer; 4. Lower electrode layer; 5. Lower flexible substrate layer; 30. Flexible pressure-sensitive layer; 31. Flexible insulating separator layer; 310. Through hole. Detailed Implementation

[0027] The technical solutions provided by the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, if terms such as "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer" are used to indicate the orientation or positional relationship, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] like Figures 1 to 3 As shown, the present invention provides a pressure sensor based on a flexible conductive polymer film, which includes an upper flexible substrate layer 1, an upper electrode layer 2, a pressure-sensitive functional layer 3, a lower electrode layer 4, and a lower flexible substrate layer 5 arranged sequentially from top to bottom. The pressure-sensitive functional layer 3 includes several flexible pressure-sensitive layers 30 and several flexible insulating separation layers 31. The flexible insulating separation layers 31 are provided with a plurality of through holes 310 at intervals. When the pressure-sensitive functional layer 3 is subjected to pressure, the flexible pressure-sensitive layer 30 contacts and conducts through the through holes 310 with another adjacent flexible pressure-sensitive layer 30, upper electrode layer 2, or lower electrode layer 4.

[0030] It should be noted that the pressure-sensitive functional layer is conductive and can undergo elastic deformation under pressure. When the pressure is sufficient to cause the elastic deformation of the pressure-sensitive functional layer to contact the adjacent conductor (another flexible pressure-sensitive layer, upper electrode layer, or lower electrode layer) through the through-hole, a sudden change in current and resistance occurs. The current or resistance monitoring system connected to the pressure sensor can then obtain the corresponding electrical signal, thus realizing the basic sensing function of converting mechanical pressure into an electrical signal. When there is no external pressure or the external pressure is too small to reach the lower limit of the monitoring pressure, the flexible insulating separator mainly serves as an insulating layer, keeping the entire pressure-sensitive functional layer in a high-resistance (open circuit) state. In this case, even if the sensor is energized with a working voltage on both sides, no current will be generated, resulting in good energy-saving effect. The lower limit of the monitoring pressure can be continuously and flexibly adjusted by changing the thickness of the flexible insulating separator, and can also be adjusted by controlling the size of the through-hole, the elasticity of the flexible pressure-sensitive layer, and its conductivity.

[0031] In one embodiment of the present invention, such as Figure 1 and Figure 3As shown, the pressure-sensitive functional layer 3 includes two flexible pressure-sensitive layers 30 and a flexible insulating separator layer 31, with the flexible insulating separator layer 31 located between the two flexible pressure-sensitive layers 30.

[0032] It should be noted that in the pressure sensor described above, when the sensor is subjected to external mechanical pressure, both flexible pressure-sensitive layers undergo elastic deformation. In the area corresponding to the through-hole, the elastically deformed parts of the flexible pressure-sensitive layers extend into the through-hole and gradually contact and adhere to it. This process causes a change in the conductivity of the pressure-sensitive functional layer, allowing pressure monitoring by observing changes in resistance and current. After the external pressure disappears, the two flexible pressure-sensitive layers rebound to their original shape, and the flexible insulating separator layer once again provides insulation.

[0033] It is understandable that, since the upper and lower flexible pressure-sensitive layers extend into the through hole and make contact with each other through the elastic deformation at the same time, its sensitivity to pressure is relatively higher than that of a single flexible pressure-sensitive layer with single elastic deformation.

[0034] In one embodiment of the present invention, the pressure-sensitive functional layer 3 includes a flexible pressure-sensitive layer 30 and a flexible insulating separator layer 31, wherein the flexible insulating separator layer 31 is located between the flexible pressure-sensitive layer 30 and the upper electrode layer 2 or between the flexible pressure-sensitive layer 30 and the lower electrode layer 4.

[0035] It should be noted that, as Figure 2 and Figure 3 As shown, the flexible insulating separator is located between the flexible pressure-sensitive layer and the lower electrode layer. When external mechanical pressure is applied, the flexible pressure-sensitive layer undergoes elastic deformation. The area at the bottom corresponding to the through hole protrudes downward and contacts and conducts through the through hole with the lower electrode layer. As a result, the resistance between the upper and lower electrode layers of the sensor changes significantly, and the current changes abruptly. Based on this, the pressure applied to the pressure sensor can be reflected by the monitored electrical signal.

[0036] It is understood that, in addition to the two types of pressure sensors mentioned above, the present invention can also provide a pressure sensor composed of more flexible pressure-sensitive layers and flexible insulating separators, with one or two flexible insulating separators sandwiched between adjacent flexible pressure-sensitive layers.

[0037] In one embodiment of the present invention, the flexible pressure-sensitive layer 30 and the flexible insulating separator layer 31 are bonded and fixed to each other by a flexible adhesive, wherein the flexible adhesive is a flexible epoxy resin adhesive or an acrylic resin adhesive.

[0038] It should be noted that flexible adhesives are not limited to flexible epoxy resin or acrylic resin adhesives; other adhesives with good flexibility can also be used to ensure that the sensor has good flexibility and deformation capability after bonding. Flexible adhesives are also preferred when bonding the upper and lower electrode layers to the upper and lower surfaces of the pressure-sensitive functional layer.

[0039] In one embodiment of the present invention, such as Figure 3 As shown, the flexible insulating separator 31 is a PI film, PET film or PDMS film with the through holes 310 evenly distributed. The thickness of the flexible insulating separator 31 is 0.05-0.25mm, and the through holes 310 are round holes, elliptical holes or polygonal holes.

[0040] It should be noted that the through holes distributed on the flexible insulating separator layer can be achieved through the specific structural design of the mold during the molding of the corresponding film (such as PDMS film), or they can be directly cut in one step by a die-cutting mold after the film is molded.

[0041] In one embodiment of the present invention, the through hole 310 is a round hole or a square hole, with a corresponding diameter or side length of 0.5-5mm.

[0042] In one embodiment of the present invention, the upper flexible substrate layer 1 and the lower flexible substrate layer 5 are PI film, PET film or PDMS film.

[0043] In one embodiment of the present invention, the upper electrode layer 2 and the lower electrode layer 4 are metal conductive layers or conductive ink layers formed on the corresponding surfaces of the upper flexible substrate layer 1 and the lower flexible substrate layer 5.

[0044] It should be noted that the metal conductive layer can be a copper, silver, or gold film formed on the corresponding flexible substrate layer by magnetron sputtering, and the conductive ink layer can be printed from conductive ink containing conductive silver paste or conductive polymer.

[0045] In one embodiment of the present invention, the flexible pressure-sensitive layer 30 is a flexible conductive polymer film with elasticity and containing conductive filler, and the thickness of the flexible conductive polymer film is 0.25-1mm.

[0046] Specifically, flexible conductive polymer films with elasticity and containing conductive fillers can be prepared by incorporating a certain amount of conductive material with good conductivity into a highly elastic polymer. For example, PDMS prepolymer, curing agent, micron-sized silver flakes (or nano-silver), and nano-carbon graphite particles are mixed and then cured to form the film, and the preparation method is referenced in Chinese Invention Patent CN2020101916063; or porous flexible pressure-sensitive layers can be prepared using PDMS, multi-walled carbon nanotubes, gallium indium liquid metal, etc. as raw materials, and the preparation method is referenced in CN2024102679078.

[0047] The present invention also provides a method for preparing the above-mentioned pressure sensor, which includes the following steps:

[0048] S1. A conductive layer is formed on a flexible substrate by magnetron sputtering or printing technology, and the substrate is cut to form an upper flexible substrate layer 1 with an upper electrode layer 2 and a lower flexible substrate layer 5 with a lower electrode layer 4, for later use.

[0049] S2. Prepare several layers of flexible pressure-sensitive layer 30 and several layers of flexible insulating separation layer 31, and bond the flexible pressure-sensitive layer 30 and the flexible insulating separation layer 31 together with flexible adhesive to form the pressure-sensitive functional layer 3;

[0050] S3. The upper flexible substrate layer 1 with the upper electrode layer 2, the lower flexible substrate layer 5 with the lower electrode layer 4, and the pressure-sensitive functional layer 3 are bonded and fixed with flexible adhesive to obtain the pressure sensor.

[0051] It should be noted that the flexible pressure-sensitive layer is a flexible conductive polymer film with elasticity and containing conductive fillers. There are many types of such films, and the preparation methods are existing technologies, so they will not be described in detail here. The porous flexible insulating separator layer is obtained by die-cutting uniformly distributed through holes from PI film, PET film, or PDMS.

[0052] It is understood that the pressure sensor provided by the present invention has both the sensing performance of conventional resistive flexible pressure sensors where the resistance changes with pressure (the conductive network in the flexible pressure-sensitive layer becomes more compact and forms or increases the conductive path as the pressure increases), and the function of consuming virtually no power when there is no pressure or the pressure reaches the lower limit of the monitoring pressure (initial pressure) during continuous pressure monitoring. At the same time, the lower limit of the monitoring pressure can be flexibly adjusted during production by changing the thickness of the flexible insulating separator layer.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressure sensor based on a flexible conductive polymer thin film, characterized in that, The structure includes an upper flexible substrate layer (1), an upper electrode layer (2), a pressure-sensitive functional layer (3), a lower electrode layer (4), and a lower flexible substrate layer (5) arranged sequentially from top to bottom. The pressure-sensitive functional layer (3) includes several flexible pressure-sensitive layers (30) and several flexible insulating separator layers (31). The flexible insulating separator layer (31) is provided with multiple through holes (310) at intervals. When the pressure-sensitive functional layer (3) is subjected to pressure, the flexible pressure-sensitive layer (30) makes contact and conduction with the adjacent flexible pressure-sensitive layer (30), upper electrode layer (2), or lower electrode layer (4) through the through holes (310).

2. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The pressure-sensitive functional layer (3) includes two flexible pressure-sensitive layers (30) and a flexible insulating separator layer (31), with the flexible insulating separator layer (31) located between the two flexible pressure-sensitive layers (30).

3. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The pressure-sensitive functional layer (3) includes a flexible pressure-sensitive layer (30) and a flexible insulating separator layer (31). The flexible insulating separator layer (31) is located between the flexible pressure-sensitive layer (30) and the upper electrode layer (2) or between the flexible pressure-sensitive layer (30) and the lower electrode layer (4).

4. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The flexible pressure-sensitive layer (30) and the flexible insulating separator layer (31) are bonded and fixed to each other by a flexible adhesive, which is a flexible epoxy resin adhesive or an acrylic resin adhesive.

5. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The flexible insulating separator (31) is a PI film, PET film or PDMS film with the through holes (310) evenly distributed. The thickness of the flexible insulating separator (31) is 0.05-0.25mm. The through holes (310) are round holes, elliptical holes or polygonal holes.

6. A pressure sensor based on a flexible conductive polymer film according to claim 5, characterized in that, The through hole (310) is a round hole or a square hole, with a corresponding diameter or side length of 0.5-5mm.

7. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The upper flexible substrate layer (1) and the lower flexible substrate layer (5) are PI film, PET film or PDMS film.

8. A pressure sensor based on a flexible conductive polymer film according to claim 1, characterized in that, The upper electrode layer (2) and the lower electrode layer (4) are metal conductive layers or conductive ink layers formed on the corresponding surfaces of the upper flexible substrate layer (1) and the lower flexible substrate layer (5).

9. A pressure sensor based on a flexible conductive polymer film according to any one of claims 1 to 8, characterized in that, The flexible pressure-sensitive layer (30) is a flexible conductive polymer film with elasticity and containing conductive filler, and the thickness of the flexible conductive polymer film is 0.25-1mm.

10. A method for preparing a pressure sensor as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. A conductive layer is formed on a flexible substrate by magnetron sputtering or printing technology, and an upper flexible substrate layer (1) with an upper electrode layer (2) and a lower flexible substrate layer (5) with a lower electrode layer (4) are cut and prepared for later use. S2. Prepare several layers of flexible pressure-sensitive layer (30) and several layers of flexible insulating separator layer (31), and bond the flexible pressure-sensitive layer (30) and the flexible insulating separator layer (31) together with flexible adhesive to form the pressure-sensitive functional layer (3). S3. The upper flexible substrate layer (1) with the upper electrode layer (2), the lower flexible substrate layer (5) with the lower electrode layer (4) and the pressure-sensitive functional layer (3) are bonded and fixed with flexible adhesive to obtain the pressure sensor.

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