Method for manufacturing flexible electrode sheet and flexible capacitive pressure array sensor

Abstract

The application provides a preparation method of a flexible electrode sheet and a flexible capacitive pressure array sensor. An elastic conductive fabric is adhered to a surface of a transfer material; then the elastic conductive fabric is cut into a plurality of conductive strips parallel to each other and spaced apart; a first flexible insulating isolation layer is adhered to an upper surface of the strip-shaped elastic conductive fabric, and then the transfer material is separated from the strip-shaped elastic conductive fabric; finally, a second flexible insulating isolation layer is adhered to a lower surface of the strip-shaped elastic conductive fabric, so that the strip-shaped elastic conductive fabric is clamped between the first flexible insulating isolation layer and the second flexible insulating isolation layer. The method is simple and easy to operate, and can be continuously and batch-prepared, and has a great production and application prospect. The prepared flexible electrode sheet can be used as an upper electrode layer and a lower electrode layer for the flexible capacitive pressure array sensor.

Description

Technical Field

[0001] This invention relates to the fields of flexible electronics and sensor technology, and particularly to a method for fabricating flexible electrode sheets and a flexible capacitive pressure array sensor. Background Technology

[0002] With the development of wearable technology, especially the rise of smart clothing and smart wearables, the contact interface has changed from the traditional rigid and regular contact interface to the flexible and irregular contact interface. Therefore, in order to realize the acquisition of data such as stress on flexible and irregular contact interfaces, the sensor has also changed from the traditional rigid sensor to the flexible wearable sensor, especially the pressure array sensor, which has received widespread attention.

[0003] Currently, research on flexible pressure array sensors mainly focuses on resistive, capacitive, and piezoelectric types, and resistive pressure array sensors are the most commonly used for mass production and continuous manufacturing. These resistive pressure array sensors are primarily fabricated using flexible substrates such as PI or PET, on which interdigital electrodes and pressure-sensitive layers are printed. While the flexible substrate possesses a certain degree of flexibility and can be bent, the interdigital electrodes and pressure-sensitive materials cannot be folded or twisted freely with the substrate. This limits the application of this type of pressure array sensor in applications requiring higher flexibility, such as folding and arbitrary twisting. Summary of the Invention

[0004] In view of the above-mentioned technical status, the present invention provides a method for preparing flexible electrode sheets. This method is simple, easy to operate, and can be prepared continuously and in batches, and has great prospects for production application.

[0005] The technical solution provided by this invention is: a method for preparing a flexible electrode sheet, wherein the flexible electrode sheet comprises a first flexible insulating layer, a second flexible insulating layer, and a plurality of spaced and parallel conductive strips sandwiched between the first and second flexible insulating layers; the preparation method includes the following steps.

[0006] (1) As Figure 1 As shown in Figure (a), the elastic conductive fabric 20 is bonded to the surface of the transfer material 10;

[0007] The transfer material 10 is viscous at room temperature and can adhere to the elastic conductive fabric 20. When heated under certain conditions, its viscous properties can be reduced or even lost, thereby allowing it to separate from the elastic conductive fabric 20.

[0008] (2) Figure 1As shown in Figure (b), the elastic conductive fabric 20 is cut so that the elastic conductive fabric 20 forms several parallel conductive strips on the surface of the transfer material 10, and there is a gap between adjacent conductive strips to form a strip-shaped elastic conductive fabric 21, while the transfer material 10 is not cut and remains intact or the cutting depth of the transfer material 10 is less than the thickness of the transfer material 10.

[0009] (3) Figure 1 As shown in Figure (c), the first flexible insulating layer 31 is bonded to the surface of the strip-shaped elastic conductive fabric 21; then, as .... Figure 1 As shown in Figure (d), the transfer material 10 is separated from the strip-shaped elastic conductive fabric 21;

[0010] (4) Figure 1 As shown in Figure (d), the second flexible insulating layer 32 is bonded to the lower surface of the strip-shaped elastic conductive fabric 21, that is, the strip-shaped elastic conductive fabric 21 is sandwiched between the first flexible insulating layer 31 and the second flexible insulating layer 32.

[0011] Preferably, both the elastic conductive fabric and the transfer material are rolls.

[0012] The transfer material is not limited and can be commercially available materials, such as heat-release film based on PET substrate. The viscosity of the transfer material can be reduced or even lost by controlling the heating temperature, heating time, and the pressure applied during heating.

[0013] Preferably, the thickness of the transfer material is greater than or equal to 0.04 mm.

[0014] The specific material of the elastic conductive fabric is not limited, but preferably it has high conductivity and a resistivity of less than or equal to 500 mΩ·cm.

[0015] In step (1), the bonding method between the elastic conductive fabric and the transfer material is not limited, including bonding under mechanical pressure at room temperature and bonding by heating, or both. As a further preferred option, the mechanical pressure is adjustable, preferably pneumatically adjustable.

[0016] In step (2), the cutting method is not limited, including one or more of mechanical cutting, ultrasonic cutting, thermal cutting, and laser cutting. Preferably, a cutting machine is used to cut the elastic conductive fabric. More preferably, the parameters of the cutting machine are adjustable; by adjusting the parameters, the elastic conductive fabric is cut to form the strip-shaped elastic conductive fabric. Preferably, the width of the conductive strip is adjustable, and the spacing between adjacent conductive strips is adjustable. More preferably, the width of each conductive strip is greater than or equal to 0.1 mm. More preferably, the spacing between adjacent conductive strips is greater than or equal to 0.1 mm. More preferably, the minimum spacing between adjacent conductive strips is related to the slitting line width of the cutting head on the elastic conductive fabric; the spacing between adjacent conductive strips can be adjusted by adjusting the slitting line width.

[0017] In step (3), as one implementation method, when the first flexible insulating isolation layer 31 is bonded to the surface of the strip-shaped elastic conductive fabric 21, the bonding is carried out under mechanical pressure, and heating is performed at the same time. The heating conditions are such that the transfer material reduces or loses its stickiness, thereby enabling the transfer material 10 to be separated from the strip-shaped elastic conductive fabric 21.

[0018] Both the first and second flexible insulating layers possess adhesiveness and conductive insulation properties. The materials are not limited, but are preferably insulating elastic polymer materials, such as one or more of thermoplastic elastomers (TPE), thermoplastic polyurethane elastomers (TPU), ethylene-vinyl acetate copolymers (EVA), and EAA (acetic acid-acrylic acid copolymer). To make the first and second flexible insulating layers adhesive, or to improve the adhesiveness between them, double-sided adhesive can be applied to the surfaces of the first and second flexible insulating layers respectively, or adhesive can be applied to the back of the first and second flexible insulating layers.

[0019] The first flexible insulating layer and the second flexible insulating layer can be made of the same material or different materials.

[0020] According to actual needs, the flexible electrode sheet obtained in step (4) can be cut to a certain size.

[0021] The preparation method of the present invention can be implemented in multiple steps on a single laminating machine, or it can be continuously produced on a production line including multiple equipment such as laminating machines. The laminating machine is preferably a fully automatic laminating machine, including a feeding rack, pressure rollers, heating device, winding rack, and synchronous film peeling device, etc.

[0022] The flexible electrode sheet prepared using this invention can be used in flexible electronic devices, possessing advantages such as high flexibility and the ability to be bent, folded, and twisted. For example, it can be used as the upper and lower electrode layers to form a flexible capacitive pressure array sensor. This sensor includes an upper electrode layer, a lower electrode layer, and an elastic dielectric layer located between the upper and lower electrode layers. The conductive strips in the upper electrode layer intersect with the conductive strips in the lower electrode layer. The conductive strips of the upper and lower electrode layers are connected by electrode leads.

[0023] The material of the elastic dielectric layer is not limited, including polyurethane foam, EVA foam, foamed rubber, foamed silicone, etc. with porous structure, or elastic fabric, elastic silicone, etc. without porous structure.

[0024] Preferably, the number of electrode leads is the same as the number of conductive strips in the upper electrode layer and the same as the number of conductive strips in the lower electrode layer. One end of each electrode lead is connected to a conductive strip in the upper electrode layer in a one-to-one correspondence, and the other end is connected to a conductive strip in the upper electrode layer in a one-to-one correspondence.

[0025] Preferably, the connection method between the electrode leads and the conductive strips in the upper electrode layer is not limited, such as fixing with conductive adhesive, welding, etc.

[0026] Preferably, the connection method between the electrode leads and the conductive strips in the lower electrode layer is not limited, such as fixing with conductive adhesive, welding, etc.

[0027] Preferably, the flexible capacitive pressure array sensor further includes an encapsulation layer and a shielding layer. The shielding layer is used to shield and encapsulate the flexible capacitive pressure array sensor, preventing interference from electrode leads and external environmental noise. The shielding layer material can be a flexible material, including but not limited to conductive fiber fabric, carbon paste cloth, and textiles with a conductive coating. The encapsulation layer material can be a flexible textile material. The encapsulation method is not limited and can employ one or more of the following methods: dispensing, adhesive bonding, and thermoforming.

[0028] Preferably, the flexible capacitive pressure array sensor further includes an insulating layer for insulatingly encapsulating the shielding layer and preventing accidental contact due to leakage.

[0029] Preferably, electrode leads are disposed at the end regions of the upper and lower electrode layers, forming electrode lead regions. More preferably, a shielding layer is disposed around the electrode lead regions to completely shield them.

[0030] Preferably, the insulating layer is wrapped around the shielding layer to completely insulate the electrode lead area.

[0031] Preferably, the encapsulation layer includes an upper encapsulation layer and a lower encapsulation layer for assembling and encapsulating the flexible capacitive pressure array sensor.

[0032] Preferably, reinforcing components are added to the electrode lead area to resist external forces and improve the reliability of the conductive connection.

[0033] As a preferred option, the electromagnetic shielding part is insulated and encapsulated to prevent accidental contact due to leakage.

[0034] Preferably, a connector key is provided in the electrode lead area to facilitate interface matching and connection with an external controller for row and column electrode signal scanning.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) This invention proposes a method for preparing flexible electrodes. This method is simple and easy to operate, and can produce an array of parallel electrode strips. It can be bent, folded and twisted at will, and can be well adapted to fully flexible electronic application scenarios, such as electronic products that come into contact with the human body, such as smart clothing, cushions and mattresses. It has a high degree of fit with the human body, is thin and flexible, and can realize electronic information detection and interactive feedback on flexible and irregularly shaped contact surfaces.

[0037] (2) The flexible electrode of the present invention can be prepared continuously and in batches, and has great prospects for production and application.

[0038] (3) The present invention provides a flexible capacitive pressure array sensor, which can realize the continuous and batch preparation of the electrode layer in the flexible capacitive pressure array sensor, thereby promoting the continuous and batch production of the flexible capacitive pressure array sensor. Attached image description:

[0039] Figure 1 This is a schematic diagram of the fabrication process of the flexible electrode sheet of the present invention.

[0040] Figure 2 This is a schematic diagram of the flexible electrode sheet fabrication process in Embodiment 1 of the present invention.

[0041] Figure 3 This is a schematic diagram of the cross-sectional structure of the capacitive pressure array sensor in Embodiment 2 of the present invention.

[0042] Figure 4 yes Figure 3 A top view of the functional components of a capacitive pressure array sensor.

[0043] Figure 1 The reference numerals in the figures are: transfer material 10, elastic conductive fabric 20, strip-shaped elastic conductive fabric 21, first flexible insulating layer 31, and second flexible insulating layer 32.

[0044] Figure 2The reference numerals in the figures are as follows: elastic conductive fabric 401, transfer material 402, first laminating machine 403-1, second laminating machine 403-2, third laminating machine 403-3, laser cutting machine 404, first flexible insulating isolation layer 405, composite material of strip-shaped elastic conductive fabric and upper isolation layer 406, debonded transfer material 407, second flexible insulating isolation layer 408, three-layer composite film material 409.

[0045] Figure 3-4 The reference numerals in the figures are: upper encapsulation layer 101, insulating layer 102, shielding layer 103, upper electrode layer 104, elastic dielectric layer 105, lower electrode layer 106, lower encapsulation layer 107, conductive strip 202, ribbon cable lead 203, and electrode lead area 204. Detailed implementation method:

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and are not intended to limit the present invention.

[0047] In this embodiment, the flexible electrode sheet is manufactured using a roll-to-roll transfer continuous fabrication process. For example... Figure 2 The continuous production line includes multiple pieces of equipment, such as the first laminating machine 403-1, the second laminating machine 403-2, and the third laminating machine 403-3, a cutting machine 404, and other auxiliary equipment. The three laminating machines are fully automatic laminating machines of the same model and specifications, equipped with upper and lower feeding racks, upper and lower auxiliary material winding racks, pressure rollers, heating devices, composite material winding racks, and meter counters. The cutting machine 404 is a laser cutting machine; the laser head focal length, energy intensity, and running speed can all be adjusted and set, and its running path can be determined by drawing software.

[0048] In this embodiment, the elastic conductive fabric 401 is made of silver fiber textile with a resistivity of less than or equal to 200 mΩ·cm and a weight of 30-100 g / cm.

[0049] The first flexible insulating layer 405 is made of EVA film roll material with adhesive backing. The EVA film thickness is 20-25μm, and the adhesive is an acrylic adhesive with adhesive backing parameters of 60-100g / ㎡. The second flexible insulating layer 408 uses the same EVA film roll material as the first flexible insulating layer 405, but it is not treated with adhesive backing.

[0050] The transfer material 402 is a heat-release film based on a PET substrate with a thickness of 80-120 μm. The heat-release film has low viscosity at room temperature, and after heating for a certain period, its viscosity completely disappears, resulting in release. In this embodiment, under the conditions of a heating temperature of 130°C, a heating time of 20 seconds, and an applied air pressure of 0.2 MPa, the heat-release film can de-adhere and cannot regain its tackiness.

[0051] In this embodiment, the fabrication process of the flexible electrode sheet is as follows: Figure 2 As shown, it includes the following steps:

[0052] (1) On the first laminating machine 403-1 of the continuous production line, the elastic conductive fabric 401 roll is bonded to the upper surface of the transfer material 402 under normal temperature pressure conditions, with a pressure of 0.2MPa.

[0053] (2) The film material bonded in step (1) does not need to be rolled up and is directly cut by the laser cutting machine 404. By adjusting the focal length of the laser head, the laser energy and the laser cutting speed, the laser cutting machine cuts the composite film material of elastic conductive fabric and transfer material in a half-cut state, that is, only the elastic conductive fabric is cut and the transfer material is not cut, so that the elastic conductive fabric forms several parallel conductive strips on the surface of the transfer material. The spacing between adjacent conductive strips is defined by the laser cutting width of the elastic conductive fabric, which is about 0.2mm. In this embodiment, an auxiliary material recycling device is configured at the exit of the laser cutting machine 404 and before the second laminating machine 403-2 to recycle the unwanted parts of the elastic conductive fabric cut by the laser.

[0054] (3) The strip-shaped elastic conductive fabric and the transfer material composite film after laser cutting in step (2) enter the second laminating machine 403-2. On the second laminating machine 403-2, the first flexible insulating isolation layer 405 is bonded to the upper surface of the strip-shaped elastic conductive fabric and the transfer material composite film under pressure of 0.3 MPa to obtain the composite material 406. At the same time, the composite material 406 is heated to 130°C for 20 seconds with an applied air pressure of 0.2 MPa to de-adhere the transfer material 402 and form the de-adheded transfer material 407, which is then peeled off from the composite material 406 and wound up to obtain the composite material 406 after the transfer material has been peeled off.

[0055] (4) The composite material 406 after peeling off the transfer material enters the third laminating machine 403-3. On the third laminating machine 403-3, the composite material 406 after peeling off the transfer material is bonded to the surface of the second flexible insulating isolation layer 408 under pressure conditions of 0.3MPa to obtain a three-layer composite material 409. After lamination, the rough edges of the composite material are cut and trimmed using the cutter holder of the laminating machine. The three-layer composite material 409 is then wound up using the take-up rack to obtain the flexible electrode sheet material.

[0056] The flexible electrode material prepared above can be used in flexible capacitive pressure array sensors. For example... Figure 3As shown, the flexible capacitive pressure array sensor includes, from top to bottom, an upper encapsulation layer 101, an insulating layer 102, a shielding layer 103, an upper electrode layer 104, an elastic dielectric layer 105, a lower electrode layer 106, and a lower encapsulation layer 107.

[0057] The upper electrode layer 104 and the lower electrode layer 106 are respectively obtained from the flexible electrode sheet prepared above, that is, they are cut from the flexible electrode sheet prepared above according to the size of the upper electrode layer 104 and the lower electrode layer 106.

[0058] In this embodiment, the conductive strip in the upper electrode layer 104 and the conductive strip in the lower electrode layer 106 are electrically connected by a ribbon cable 203. The ribbon cable 203 is disposed in the end regions of the upper electrode layer 104 and the lower electrode layer 106 to form an electrode lead area 204.

[0059] In this embodiment, the upper electrode layer 10, the elastic dielectric layer 105, and the lower electrode layer 106 are assembled by interlayer bonding using edge local dispensing to form a capacitive pressure array sensor functional component. The shielding layer 103 is wrapped around the electrode lead area using dispensing, and the insulating layer 102 is wrapped around the shielding layer 103 using dispensing, completely bonding and encapsulating the electrode lead area. The upper encapsulation layer 101 and the lower encapsulation layer 108 are assembled and encapsulated with the capacitive pressure array sensor functional component using edge local dispensing.

[0060] In this embodiment, the upper encapsulation layer 101 and the lower encapsulation layer 107 are made of the same material, both being 100g matte polyester taffeta. Polyester taffeta is a type of polyester fabric that is cost-effective, lightweight, thin, smooth, and not easily wrinkled or deformed, maintaining a good appearance. Furthermore, the fabric has excellent abrasion resistance. Used as an external encapsulation layer for the sensor, it can both protect the sensor from damage and maintain the relatively fixed position of the sensing unit. In addition, polyester taffeta emits a distinct pungent odor when burned, serving as a fire warning and safety feature.

[0061] In this embodiment, the insulation layer 102 is made of composite polyester fabric with TPU coating, which has an insulation resistance greater than or equal to 20MΩ and has waterproof, anti-corrosion and antistatic properties.

[0062] In this embodiment, the shielding layer 103 is a carbon film, and the sheet resistance of the carbon film is 10. -1 -10 2 Ω / □, film thickness 10-100μm.

[0063] In this embodiment, the elastic dielectric layer 105 is made of open-cell foamed rubber EPDM (ethylene propylene diene monomer rubber) material with large compression deformation.

[0064] The embodiments described above provide a detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flexible electrode sheet, characterized in that: Includes the following steps: (1) Adhere the elastic conductive fabric (20) to the surface of the transfer material (10); The transfer material (10) is viscous at room temperature and can be bonded to the elastic conductive fabric. When heated under certain conditions, its viscous properties can be reduced or even lost, thereby allowing it to separate from the elastic conductive fabric (20). (2) Cut the elastic conductive fabric (20) so that the elastic conductive fabric (20) forms several parallel conductive strips on the surface of the transfer material, and there is a gap between adjacent conductive strips to form a strip-shaped elastic conductive fabric (21), while the transfer material (10) is not cut and remains intact or the cutting depth of the transfer material (10) is less than the thickness of the transfer material 10. (3) The first flexible insulating layer (31) is bonded to the upper surface of the strip-shaped elastic conductive fabric (21); then, the transfer material 10 is separated from the strip-shaped elastic conductive fabric (21); (4) The second flexible insulating layer (32) is bonded to the lower surface of the strip-shaped elastic conductive fabric (21), that is, the strip-shaped elastic conductive fabric (21) is sandwiched between the first flexible insulating layer 31 and the second flexible insulating layer (32).

2. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: Both the elastic conductive fabric and the transfer material are rolls.

3. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: In step (2), the cutting method includes one or more of mechanical cutting, ultrasonic cutting, thermal cutting, and laser cutting.

4. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: In step (2), the elastic conductive fabric (20) is cut using a cutting machine.

5. The method for preparing the flexible electrode sheet as described in claim 4, characterized in that: The parameters of the cutting machine are adjustable. By adjusting the equipment parameters, the elastic conductive fabric can be cut to form the strip-shaped elastic conductive fabric.

6. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: The width of the conductive strip is adjustable, and the spacing between adjacent conductive strips is adjustable.

7. The method for preparing the flexible electrode sheet as described in claim 6, characterized in that: The width of each conductive strip is greater than or equal to 0.1 mm.

8. The method for preparing the flexible electrode sheet as described in claim 6, characterized in that: The spacing between adjacent conductive strips is greater than or equal to 0.1 mm.

9. The method for preparing the flexible electrode sheet as described in claim 6, characterized in that: The spacing between adjacent conductive strips can be adjusted by changing the width of the slit line.

10. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: In step (3), bonding is performed under mechanical pressure while heating is carried out. The heating conditions are such that the transfer material reduces or loses its stickiness and can be separated from the elastic conductive fabric.

11. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: The flexible electrode sheet obtained in step (4) is cut to a certain size.

12. The method for preparing the flexible electrode sheet as described in claim 1, characterized in that: It can be achieved in multiple steps on a single laminating machine, or continuously on equipment that includes multiple laminating machines.

13. A flexible capacitive pressure array sensor, comprising an upper electrode layer, a lower electrode layer, and an elastic dielectric layer located between the upper electrode layer and the lower electrode layer, characterized in that: The flexible electrode sheet prepared by the method according to any one of claims 1 to 12 is used as the upper electrode layer and the lower electrode layer; The conductive strips of the upper electrode layer intersect with those of the lower electrode layer; the conductive strips of the upper electrode layer and the lower electrode layer are connected by electrode leads.

14. The flexible capacitive pressure array sensor as described in claim 13, characterized in that: The number of electrode leads is the same as the number of conductive strips in the upper electrode layer and the same as the number of conductive strips in the lower electrode layer. One end of each electrode lead is connected to a conductive strip in the upper electrode layer in a one-to-one correspondence, and the other end is connected to a conductive strip in the upper electrode layer in a one-to-one correspondence.

15. The flexible capacitive pressure array sensor as described in claim 13, characterized in that: The flexible capacitive pressure array sensor also includes an encapsulation layer and a shielding layer.

16. The flexible capacitive pressure array sensor as described in claim 15, characterized in that: Electrode leads are placed at the end regions of the upper and lower electrode layers, forming electrode lead areas; a shielding layer is placed around the electrode lead areas.

17. The flexible capacitive pressure array sensor as described in claim 15, characterized in that: It also includes an insulating layer for insulating and encapsulating the shielding layer.

18. The flexible capacitive pressure array sensor as described in claim 17, characterized in that: An insulating layer is wrapped around the shielding layer to completely insulate the electrode lead area.

19. The flexible capacitive pressure array sensor as described in claim 15, characterized in that: Add reinforcement components to the electrode lead area.

20. The flexible capacitive pressure array sensor as described in claim 15, characterized in that: Connectors are installed in the electrode lead area.

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