Minimum port interdigital sensor array based on screen printing and its preparation method

Abstract

The present invention discloses a screen-printed minimum-port interdigital sensor array and its preparation method, belonging to the field of flexible wearable electronics and micro-nano sensor devices. The preparation method of the interdigital sensor array includes the following steps: S1, preparing an interdigital electrode layer; S2, coating a first insulating layer; S3, coating an electrode layer conductor; S4, coating a second insulating layer; S5, coating a spacer layer; S6, preparing a sensitive layer; S7, packaging the sensor array; aligning and bonding the electrode layer-first insulating layer-electrode layer conductor-second insulating layer-spacer film prepared in S5 with the sensitive layer prepared in S6, and packaging to obtain a screen-printed minimum-port interdigital sensor array. The present invention can minimize the number of output ports of the interdigital sensor array while maintaining excellent flexibility. Furthermore, the overall mechanical properties are improved, and the array has high sensitivity and high stability.

Description

Technical Field

[0001] The present invention belongs to the field of flexible wearable electronics and micro-nano sensor devices, and particularly relates to a minimum port interdigital sensor array based on screen printing and a preparation method thereof. Background Art

[0002] Flexible sensors, a new interdisciplinary field, are booming in areas such as electronic skin, human-computer interaction, and medical diagnostics. Interdigitated electrode sensors, a classic choice for flexible sensors, have been widely discussed. However, this discussion has largely been limited to single sensors, small multi-channel sensor arrays, or large-area arrays based on flexible printed circuit boards (FPCBs). The former suffers from significant limitations in sensor integration and comprehensive information detection, while the latter suffers from mechanical disadvantages in terms of sensor flexibility, conformal attachment, and application to human skin. This is because interdigitated sensors, as a typical example of single-sided positive and negative electrodes, face the challenges of creating multi-channel sensor arrays with numerous leads and densely packed I / O ports. Minimum port outputs are designed to enable crossover of rows and columns in the sensor array, enabling sensor selection via rows and columns. This effectively reduces the number of output ports in interdigitated sensors. Currently, most solutions rely on FPCB vias, sacrificing flexibility to avoid wire crossing, which is clearly not a good option. Summary of the Invention

[0003] Based on the above technical problems, the present invention proposes a minimum port interdigital sensor array based on screen printing and a preparation method thereof.

[0004] The technical solution adopted by the present invention is:

[0005] One of the objectives of the present invention is to provide a method for preparing a minimum port interdigital sensor array based on screen printing, comprising the following steps:

[0006] S1, preparing an interdigitated electrode layer;

[0007] Selecting a flexible substrate, and performing laser etching on the flexible substrate to obtain a flexible substrate with a shading structure;

[0008] Screen-printing conductive ink on a flexible substrate with a textured structure to obtain an interdigitated electrode layer;

[0009] S2, applying a first insulating layer;

[0010] Screen-printing insulating ink on the lead overlaps on the interdigitated electrode layer to form a first insulating layer, thereby obtaining an electrode layer-first insulating layer film;

[0011] S3, coating electrode layer wire;

[0012] Screen-printing a conductive ink on the electrode layer-first insulating layer film obtained in S2 to form an electrode layer conductor interconnecting the electrodes, thereby obtaining an electrode layer-first insulating layer-electrode layer conductor film;

[0013] S4, applying a second insulating layer;

[0014] Screen-printing insulating ink on the electrode layer-first insulating layer-electrode layer wire film obtained in S3 to form a second insulating layer to prevent crosstalk, thereby obtaining an electrode layer-first insulating layer-electrode layer wire-second insulating layer film;

[0015] S5, coating the spacer layer;

[0016] Screen-printing a spacer layer ink on the electrode layer-first insulating layer-electrode layer wire-second insulating layer film obtained in S4 to form a spacer layer, thereby obtaining an electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film;

[0017] S6. preparing a sensitive layer;

[0018] Select a flexible substrate, screen-print the sensitive layer ink on the flexible substrate, and then perform laser etching to obtain the sensitive layer;

[0019] S7, sensor array packaging;

[0020] The electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film prepared in S5 is aligned and bonded with the sensitive layer prepared in S6, and then packaged to obtain a minimum port interdigital sensor array based on screen printing.

[0021] A second object of the present invention is to provide a screen-printed minimum-port interdigital sensor array prepared by the above method, wherein the interdigital sensor array comprises a sensitive layer, a spacer layer, a second insulating layer, an electrode layer conductor, a first insulating layer, and an interdigital electrode layer stacked in sequence from top to bottom;

[0022] The interdigitated electrode layer is an integrated structure formed by a first flexible substrate with a first shading structure and an interdigitated electrode array screen-printed thereon; the first insulating layer covers the overlapping portions of the leads of the interdigitated electrode array; the electrode layer wires are arranged above the first insulating layer, and the overlapping portions of the leads of the interdigitated electrode array are separated from the electrode layer wires by the first insulating layer; the electrode layer wires are connected to the interdigitated electrode array;

[0023] The second insulating layer covers the first flexible substrate, and an array through hole is provided at a position on the second insulating layer facing the interdigital electrode array;

[0024] The spacer layer includes an outer frame, and spacer bars are arranged at intervals in the inner space formed by the outer frame. The spacer bars are located at the gaps facing the interdigital electrode array, and the spacer bars include a plurality of segments.

[0025] The sensitive layer includes a second flexible substrate, on which a sensitive area array is arranged. The sensitive area array is located directly above the interdigital electrode array, and a second shading structure is etched on the sensitive area array.

[0026] The beneficial technical effects of the present invention are:

[0027] (1) The present invention can reduce the number of output ports of the interdigital sensor array as much as possible while maintaining excellent flexibility, and the overall mechanical properties are improved, with high sensitivity and high stability.

[0028] (2) The preparation method of the present invention applies screen-printed insulating ink to the intersection of the sensor wires, and realizes a "break-circuit" connection at the intersection of the sensor's "row lead" and "column lead", shielding the electrical connection while ensuring mechanical stability, thereby achieving the purpose of reducing the number of output ports. Combined with the layout of the second insulating layer, spacer layer, etc., the sensitivity and stability of the sensor are further improved. In addition, the TPU laser-engraved background pattern at the bottom of the interdigitated electrode layer and the microstructure of the sensitive layer are intertwined to form a stable "arch bridge" reinforcement structure. This overall reinforcement structure improves the conductivity, stability and mechanical properties of the composite system; compared with a single system, this improvement in mechanical properties and the conductive network of the dot-line structure have higher perception sensitivity; under certain pressure conditions, the pressure perception range is improved, thereby making the sensor highly sensitive and stable. The life of the sensor of the present invention can reach 100,000 times.

[0029] (3) The interdigital sensor array prepared by the present invention is a flexible pressure sensor that can achieve ultra-high sensitivity detection of pressure, and has the characteristics of full flexibility and greatly reduced number of output ports. The sensitive layer is made of carbon nanotubes after screen printing and then laser engraving, which increases the working range of the sensor while maintaining ultra-high sensitivity. At the same time, the transparent flexible substrate TPU at the bottom of the electrode layer is laser engraved with a background pattern, which can further improve the sensitivity, working range and other parameters of the sensor. The minimum port output is intended to achieve the row and column crossing of the sensor array. Sensor selection through rows and columns can effectively reduce the number of I / O points. The sensor array produced by screen printing with insulating ink shows good electrical shielding at the intersection of the wires, ensuring the accuracy of the sensor during the measurement process. The prepared sensor and its array show excellent capabilities in tactile sensing and physiological information detection. This provides a reliable method for the organic integration of printed electronics, interdigital sensor arrays and minimum ports.

[0030] (4) The present invention successfully reduces the number of output ports from 17 to 8, achieving electrical insulation and three-dimensional interconnection of wire intersections. The unique printing strategy provides a new approach to the production of matrix-structured interdigitated sensor arrays. The sensor array is fully screen-printed, demonstrating its outstanding flexibility. At the same time, the present invention further improves the mechanical and electrical performance of the sensor by modifying the sensitive layer and electrode layer substrate through laser engraving. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of a method for preparing a minimum port interdigital sensor array based on screen printing according to the present invention;

[0032] Figure 2 This is a schematic diagram of the structural principle of the minimum port interdigital sensor array based on screen printing produced by the present invention;

[0033] Figure 3 Schematic diagram of the structural principle of coating a first insulating layer on an interdigitated electrode array in the present invention;

[0034] Figure 4 Schematic diagram of the structural principle of the second insulating layer in the present invention;

[0035] Figure 5 Schematic diagram of the structural principle of the spacer layer in the present invention;

[0036] Figure 6 Schematic diagram of the electrode layer-first insulating layer-electrode layer conductor film in the present invention;

[0037] Figure 7 is a schematic plan view of the sensitive layer in the present invention;

[0038] Figure 8 Schematic diagram of the stretching and bending of the interdigital sensor array prepared in the present invention; a shows the stretched state, b shows the bent state, c shows the twisted state, and d shows the protruding state;

[0039] Figure 9 This is a test data diagram of the interdigital sensor array produced by the present invention.

[0040] In the figure: 1-second flexible substrate, 2-sensitive layer, 3-spacer layer, 4-second insulating layer, 5-electrode layer wire, 6-first insulating layer, 7-interdigitated electrode layer, 8-first flexible substrate;

[0041] 101 - second shading structure, 201 - sensitive area array, 301 - outer frame, 302 - spacer bar, 3021 - segment body, 401 - array through hole, 701 - interdigital electrode array, 702 - gap, 801 - first shading structure. DETAILED DESCRIPTION

[0042] This invention utilizes a planar printing process to produce a sensor array with intersecting rows and columns. By sequentially coating a first insulating layer, a second insulating layer, and other layers, the printing process effectively prevents wire crossing, achieving a minimum port output for the sensor's planar distribution. Furthermore, laser engraving of vertical groove microstructures in the interdigitated electrode layer and the sensitive layer creates a stable "arch bridge" reinforcement structure when the sensitive layer and the interdigitated electrode layer are bonded and aligned, further enhancing the stability and sensitivity of the sensor array.

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown, a method for preparing a minimum port interdigital sensor array based on screen printing includes the following steps:

[0045] S1, preparing an interdigitated electrode layer;

[0046] A flexible substrate is selected and laser-etched on one side to create a textured structure (or vertical groove microstructure). Conductive ink is then screen-printed onto the textured flexible substrate (on the textured side) to form an interdigitated electrode array. The interdigitated electrode array and the flexible substrate form an integrated structure, which is the interdigitated electrode layer.

[0047] Specifically, the flexible substrate is made of a polyurethane hot-melt adhesive film (TPU). The film is first cleaned in a plasma cleaner and then placed on the platform below a UV laser machine for vacuum adsorption before being laser etched. After etching, the film is then placed in a plasma cleaner to remove any etching residue, resulting in a flexible substrate with a textured structure.

[0048] The conductive ink is prepared by mixing slow-drying water with conductive silver paste and mixing them evenly. The conductive ink is screen-printed on the side of the flexible substrate with a shading structure to form an interdigitated electrode array, which is then heated and cured to obtain an interdigitated electrode layer. Figure 2 shown.

[0049] S2, applying a first insulating layer;

[0050] The insulating ink is screen-printed on the interdigitated electrode layer where the leads overlap to form a first insulating layer. Figure 3 As shown, an electrode layer-first insulating layer thin film is obtained.

[0051] Specifically, the interdigitated electrode layer is placed on a screen printing table, the first insulating layer screen is aligned and placed above the interdigitated electrode layer, the drying type insulating ink is inverted on the first insulating layer screen, and the scraper is tilted to print on the overlapping part of the interdigitated electrode leads; then it is placed on a heating table for heating and curing to obtain an electrode layer-first insulating layer film.

[0052] S3, coating electrode layer wire;

[0053] Conductive ink is screen-printed on the electrode layer-first insulating layer film obtained in S2 to form an electrode layer conductor for interconnecting electrodes, thereby obtaining an electrode layer-first insulating layer-electrode layer conductor film, such as Figure 6 shown.

[0054] Specifically, the conductive ink is prepared by mixing slow-drying water with a conductive silver paste until uniformly mixed. The cured electrode layer-first insulating layer film is placed on a screen printing table. The electrode layer wire screen is aligned and placed above the first insulating layer. The conductive ink is then inverted onto the electrode layer wire screen, and a squeegee is used to print at an angle at the intersection of the interdigitated electrode leads. The film is then heated on a heating table and cured to produce the electrode layer-first insulating layer-electrode layer wire film.

[0055] The first insulating layer covers the overlapping parts of the leads of the interdigitated electrode array. The electrode layer wires are arranged above the first insulating layer. The first insulating layer separates the overlapping parts of the leads of the interdigitated electrode array from the electrode layer wires. The electrode layer wires are connected to the interdigitated electrode array.

[0056] S4, applying a second insulating layer;

[0057] Screen-printing insulating ink on the electrode layer-first insulating layer-electrode layer wire film obtained in S3 forms a second insulating layer to prevent crosstalk, thereby obtaining an electrode layer-first insulating layer-electrode layer wire-second insulating layer film.

[0058] Specifically, the cured electrode layer-first insulating layer-electrode layer conductor film is placed on a screen printing table. The second insulating layer screen is aligned and placed above the film. The drying insulating ink is placed upside down on the second insulating layer screen, and the squeegee is tilted to print. The film is then placed on a heating table for heating and curing, resulting in an electrode layer-first insulating layer-electrode layer conductor-second insulating layer film.

[0059] like Figure 4 As shown, a second insulating layer covers the flexible substrate, and array through-holes are provided on the second insulating layer directly opposite the interdigital electrode array. In other words, the electrode layer, first insulating layer, and electrode layer conductive film are covered by the second insulating layer, and the interdigital electrode array is exposed through the array through-holes.

[0060] S5, coating the spacer layer;

[0061] The spacer layer ink is screen-printed on the electrode layer-first insulating layer-electrode layer wire-second insulating layer film obtained in S4 to form a spacer layer, thereby obtaining the electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film.

[0062] Specifically, a thermoplastic polyurethane elastomer is mixed with N,N-dimethylformamide and magnetically stirred to produce a spacer layer ink. The resulting cured film, consisting of an electrode layer, a first insulating layer, an electrode layer conductor, and a second insulating layer, is placed on a screen printing table. A spacer layer screen is aligned and placed above the film. The spacer layer ink is inverted onto the screen, and a squeegee is used to print at an angle to produce a film consisting of an electrode layer, a first insulating layer, an electrode layer conductor, a second insulating layer, and a spacer layer.

[0063] like Figure 5 As shown, the spacer layer includes an outer frame, and spacer bars are arranged in the inner space formed by the outer frame. The spacer bars are located in the gap opposite the interdigital electrode array, and the spacer bars include several segments. The purpose of the spacer layer is to create a gap between the interdigital electrode layer and the sensitive layer. When the sensor is subjected to pressure, the sensitive layer and the interdigital electrodes contact each other. When the pressure is removed, the gap between the sensitive layer and the interdigital electrode layer needs to be restored to its original state by the spacer layer for the next pressure measurement. In addition, the sensitive layer and the lower layers such as the interdigital electrode layer and the insulating layer need to be bonded together by the spacer layer.

[0064] S6. preparing a sensitive layer;

[0065] A flexible substrate is selected, and the sensitive layer ink is screen-printed on the flexible substrate, and then laser etching is performed to obtain the sensitive layer.

[0066] Specifically, thermoplastic polyurethane elastomer and N,N-dimethylformamide are mixed, magnetically stirred, and carbon nanotube powder is added in the stirring state to obtain sensitive layer ink.

[0067] The flexible substrate adopts a polyurethane hot melt adhesive film, which is placed in a plasma cleaning machine for cleaning and then placed on a heating table for preheating. Then, the polyurethane hot melt adhesive film is fixed on a screen printing table, a sensitive layer screen is fixed on top of the film, and the sensitive layer ink is placed upside down on the sensitive layer screen. A scraper is used for tilted printing, and after printing is completed, the film is placed on a heating table for heating and curing.

[0068] The polyurethane hot melt adhesive film is then placed on the platform below the UV laser machine, vacuum-adhesive, and laser etching is performed on the side of the polyurethane hot melt adhesive film printed with the sensitive layer ink, similarly etching the upper shading (or vertical grooves). After etching is completed, it is placed in a plasma cleaner to clean the etching residue and obtain the sensitive layer.

[0069] like Figure 2As shown, the sensitive layer is a flexible substrate on which a sensitive area array is arranged. The sensitive area array is arranged corresponding to the interdigital electrode array, and the sensitive area array is located directly above the interdigital electrode array. Figure 2 This is mainly for the convenience of illustrating the arrangement of the sensitive area array. In actual packaging, the sensitive layer needs to be turned upside down and then combined with the interdigital electrode layer.

[0070] S7, sensor array packaging;

[0071] The electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film prepared by S5 is aligned and bonded with the sensitive layer prepared by S6, placed in a vacuum heating box, evacuated, heated to 100-110°C, and heated at this temperature for 50-60 minutes, and then cooled to achieve flexible packaging, thereby obtaining a minimum port interdigital sensor array based on screen printing.

[0072] The present invention also provides a minimum port interdigital sensor array based on screen printing prepared by the above method, such as Figure 2-7 As shown, the interdigital sensor array includes a second flexible substrate 1, a sensitive layer 2, a spacer layer 3, a second insulating layer 4, an electrode layer conductor 5, a first insulating layer 6, an interdigital electrode layer 7, and a first flexible substrate 8, which are stacked in sequence from top to bottom. The interdigital electrode layer 7 is an integrated structure formed by the first flexible substrate 8 with a first shading structure 801 and an interdigital electrode array 701 screen-printed on the first shading structure. The first insulating layer 6 covers the overlapping leads of the interdigital electrode array 701 and is a plurality of isolated sheet-like structures. The electrode layer conductor 5 is arranged above the first insulating layer 6, and the first insulating layer 6 separates the overlapping leads of the interdigital electrode array from the electrode layer conductor 5, which is connected to the interdigital electrode array 701. The second insulating layer 4 covers the first flexible substrate 8, and array through-holes 401 are provided on the second insulating layer 4 at positions directly opposite the interdigital electrode array. The spacer layer 3 includes an outer frame 301. Spacer bars 302 are interspersed within the inner space enclosed by the outer frame 301. The spacer bars are located in gaps 702 directly opposite the interdigital electrode array and include a plurality of segments 3021. The sensitive layer 2 is formed on a second flexible substrate 1. A sensitive area array 201 is arranged on the second flexible substrate 1. The sensitive area array 201 is located directly above the interdigital electrode array 701. A second shading structure 101 is etched on the sensitive area array 201.

[0073] Furthermore, when preparing the interdigitated electrode layer 7, a first shading structure 801 is etched on one side of the first flexible substrate, and an interdigitated electrode array 701 is screen-printed on the first shading structure 801. The extension direction of the first shading structure 801 is perpendicular to the direction of the interdigitated electrodes in the interdigitated electrode array 701. When preparing the sensitive layer 2, a sensitive area array 201 is screen-printed on one side of the second flexible substrate 1, and then a second shading structure 101 is etched on the sensitive area array 201. The extension direction of the second shading structure 101 is the same as that of the first shading structure 801. Figure 2 It can also be seen that the extension direction of the shading structure is perpendicular to the extension direction of the electrode layer wire 5. When the sensor array is packaged, the second flexible substrate 1 is inverted on top of the first flexible substrate 8, and the sensitive area array 201 and the interdigital electrode array 701 are arranged facing each other.

[0074] The present invention prepares an integrated structure comprising a sensitive layer, a substrate shading, and interdigital electrodes, along with a transparent flexible TPU substrate. These structures are then bonded and aligned to form a flexible interdigital sensor array. The back-end circuitry reads the sensor pressure data, and a host computer displays the pressure data. The flexible pressure sensor of the present invention achieves ultra-high-sensitivity pressure detection while being fully flexible and significantly reducing the number of output ports. The sensitive layer is screen-printed with carbon nanotubes and then laser-engraved, increasing the sensor's operating range while maintaining ultra-high sensitivity. Furthermore, the transparent flexible TPU substrate beneath the electrode layer is laser-engraved to further enhance the sensor's sensitivity, operating range, and other parameters. The minimum port output is designed to achieve crossover between rows and columns in the sensor array. Sensor selection based on rows and columns can effectively reduce the number of I / O points. The sensor array, screen-printed with insulating ink, exhibits excellent electrical shielding at the wire intersections, ensuring sensor accuracy during measurement. The resulting sensor and array demonstrate excellent capabilities in tactile sensing and physiological information detection. This invention provides a reliable method for the organic integration of printed electronics, interdigital sensor arrays, and minimum ports.

[0075] The present invention will be further described below with reference to specific embodiments.

[0076] Example 1:

[0077] A screen-printed minimum-port interdigital sensor array comprises, stacked from top to bottom, a sensitive layer, a spacer layer, a second insulating layer, electrode layer conductors, a first insulating layer, and an interdigital electrode layer. The substrate pattern and interdigital electrode array form an integrated structure on a transparent flexible substrate. The first insulating layer is positioned above the interdigital electrode array, and the electrode layer conductors are positioned above the intersection of the interdigital electrode array and the first insulating layer. The electrode layer-first insulating layer-electrode layer conductor film connects to the sensitive layer through the second insulating layer and the spacer layer.

[0078] The method for preparing the interdigital sensor array comprises the following steps:

[0079] S1, preparing the integrated structure of substrate shading and interdigital electrode array (interdigital electrode layer):

[0080] Take a culture dish, add 0.05 ml of slow-drying water and 2 g of conductive silver paste, stir for 5 minutes, and mix evenly to prepare conductive ink.

[0081] Take a 10×20cm piece 2 A 100μm thick polyurethane hot-melt adhesive film is placed in a plasma cleaner for 2-3 minutes. The film is then placed on the platform below the UV laser machine, vacuumed, and the pre-designed vertical grain structure profile is input. Laser etching is performed by adjusting the UV light power to 3-5W, the laser frequency to 60kHz, and the laser pulse width to 10us, performing 9-11 cycles of cutting. Once all contours are cut, the film is placed in a plasma cleaner for 2-3 minutes to clean any etching residue, resulting in the pre-designed flexible substrate texture structure.

[0082] The polyurethane hot melt adhesive film with laser-etched background pattern was placed on a heating table and preheated at 70°C for 2-3 minutes. The polyurethane hot melt adhesive film with laser-etched background pattern was then fixed to the screen printing table with tape, and the interdigitated electrode screen was fixed on top of the film. The prepared conductive ink was placed upside down on the screen and printed with a scraper at a 45° angle; the screen printing thickness was controlled to be 5-15um; and the printed polyurethane hot melt adhesive film was placed on a heating table at 70°C and heated for curing for 5-10 minutes to obtain a cured base background pattern and an integrated structure of the interdigitated electrode array (interdigitated electrode layer).

[0083] S2, preparing the first insulating layer:

[0084] Place the cured polyurethane hot-melt adhesive film electrode layer on a screen printing table. Align the first insulating layer stencil over the electrode layer film. Place JC JY302, a drying-type insulating ink, upside down on the first insulating layer stencil. Use a squeegee at a 45-degree angle to print at the intersection of the interdigitated electrode leads. Next, heat the printed interdigitated electrode layer and first insulating layer film on a 70°C heating table for 5-10 minutes to obtain the cured electrode layer and first insulating layer film.

[0085] S3, preparation of electrode layer wires:

[0086] The solidified interdigitated electrode layer-first insulating layer film is placed on a screen printing table, the electrode layer wire screen is highly aligned and placed above the first insulating layer, the conductive ink is inverted on the electrode layer wire screen, and the scraper is tilted 45 degrees to print on the overlapping parts of the interdigitated electrode leads; then the printed interdigitated electrode layer-first insulating layer-electrode layer wire film is placed on a 70°C heating table and heated for 5-10 minutes to obtain a solidified electrode layer-first insulating layer-electrode layer wire film, thereby forming electrode interconnection.

[0087] S4, preparing a second insulating layer:

[0088] The cured interdigitated electrode layer-first insulating layer-electrode layer conductor film is placed on a screen printing table. The second insulating layer stencil is aligned and placed above the film. JC JY302 drying-type insulating ink is placed upside down on the second insulating layer stencil, and the squeegee is tilted 45 degrees to print. The printed interdigitated electrode layer-first insulating layer-electrode layer conductor-second insulating layer film is then placed on a 70°C heating table and heated for 5-10 minutes to obtain a cured electrode layer-first insulating layer-electrode layer conductor-second insulating layer film to prevent crosstalk between different layers.

[0089] S5, prepare the spacer layer:

[0090] Take a 20ml glass bottle, add 3g of thermoplastic polyurethane elastomer, then add 5ml of N,N-dimethylformamide, put in magnetic beads, and stir thoroughly at 100℃ for 120min using a magnetic stirrer to obtain a spacer layer ink.

[0091] The solidified electrode layer - first insulating layer - electrode layer wire - second insulating layer film is placed on the screen printing table, the spacer layer screen is aligned at a high level and placed above the film, the spacer layer ink is inverted on the spacer layer screen, and the scraper is tilted 45 degrees to print to obtain the electrode layer - first insulating layer - electrode layer wire - second insulating layer - spacer layer film.

[0092] S6, preparing the sensitive layer:

[0093] In a 20ml glass bottle, add 2g of thermoplastic polyurethane elastomer, 5ml of N,N-dimethylformamide, and magnetic beads. Stir thoroughly at 100°C for 60 minutes using a magnetic stirrer. While stirring, add 0.5g of carbon nanotube powder and continue stirring at 100°C for 120 minutes to obtain the sensitive layer ink.

[0094] Take a 10×20cm piece 2A 100μm thick polyurethane hot melt adhesive film is placed in a plasma cleaner for 2-3 minutes, then preheated on a heating platform at 70°C for 2-3 minutes. The polyurethane hot melt adhesive film is then secured to the screen printing platform with tape. The sensitive layer stencil is secured above the film. The prepared sensitive layer ink is placed upside down on the stencil and printed using a squeegee at a 45° angle. The printed sensitive layer film is then placed on a 70°C heating platform for curing for 5-10 minutes to obtain the cured sensitive layer.

[0095] The sensitive layer film is placed on the platform below the UV laser machine, vacuum-attached. The pre-designed vertical grain structure profile is input. Laser etching is performed by adjusting the UV light power to 3-5W, the laser frequency to 60kHz, and the laser pulse width to 10us, performing 20-25 cycles of cutting. Once all contours are cut, the polyurethane hot melt adhesive film is placed in a plasma cleaner for 2-3 minutes to clean the etching residue, thus obtaining the pre-designed sensitive layer film.

[0096] S7, sensor package:

[0097] The electrode layer - first insulating layer - electrode layer wire - second insulating layer - spacer layer film prepared by S5 are highly aligned and bonded with the sensitive layer film prepared by S6, placed in a vacuum heating box, evacuated, heated to 100°C for 60 minutes, and cooled to achieve flexible packaging, thus completing the preparation of the minimum port interdigital sensor array based on screen printing.

[0098] The interdigital sensor array prepared in this embodiment achieves shielding between the crossed electrodes by screen-printing insulating ink, avoids the crossing of wires, and is combined with the interdigital sensor to realize the rapid preparation of a flexible pressure sensor array. Due to the introduction of insulating ink at the intersection of the wires and the rationally designed structural configuration, the output ports of the sensor are greatly reduced from 17 to 8, so as to achieve electrical insulation and three-dimensional interconnection of the wire intersections. The electrode layer and the bottom TPU laser engraved background are intertwined with the microstructure of the sensitive layer to form a stable "arch bridge" reinforcement structure. This overall reinforcement structure has a certain influence on the conductivity, stability of the composite system and the mechanical properties of the composite material. Compared with a single system, this improvement in mechanical properties and the conductive network of the point-line structure have higher perception sensitivity. Within a certain pressure range, the pressure perception range is improved, so that the sensor has high sensitivity and high stability.

[0099] Figure 8 The flexible interdigital pressure sensor array is stretched and bent, demonstrating its ultra-high flexibility. The present invention further structures the electrodes and the sensor's sensitive layer by laser engraving, further enhancing its sensitivity and stability. Figure 9This is the test data of the interdigital sensor array made by the present invention. The sensitivity of the sensor in the range of 0-15kPa is as high as 17433.3kPa -1 The sensitivity of the sensor in the range of 15-50kPa is as high as 7644.5kPa -1 .

[0100] This invention, which achieves electrical shielding between wires by screen-printing insulating ink at the interdigital electrodes, has been demonstrated to be a simple method for reducing the number of electrical output ports in flexible sensor arrays. This method can be expanded to fabricate large-area flexible interdigital electrode sensor arrays, illuminating a previously unseen area in the research of printed fully flexible, minimal-port interdigital sensors. The combination of a fully screen-printed process, the use of soft materials, and exceptional sensor performance demonstrates strong potential for applications in tactile sensing and pulse detection.

[0101] Of course, the above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention and should be protected by the present invention.

Claims

1. A method for preparing a minimum port interdigital sensor array based on screen printing, characterized in that The following steps are involved: S1, preparing an interdigitated electrode layer; Selecting a flexible substrate, and performing laser etching on the flexible substrate to obtain a flexible substrate with a shading structure; Conductive ink is screen-printed on a flexible substrate with a shading structure to form an interdigitated electrode array. The interdigitated electrode array and the flexible substrate are an integrated structure, namely the interdigitated electrode layer; S2, applying a first insulating layer; Screen-printing insulating ink on the lead overlaps on the interdigitated electrode layer to form a first insulating layer, thereby obtaining an electrode layer-first insulating layer film; The first insulating layer covers the overlapping parts of the leads of the interdigital electrode array; S3, coating electrode layer wire; Screen-printing a conductive ink on the electrode layer-first insulating layer film obtained in S2 to form an electrode layer conductor interconnecting the electrodes, thereby obtaining an electrode layer-first insulating layer-electrode layer conductor film; The electrode layer wires are arranged above the first insulating layer, and the first insulating layer separates the overlapping portion of the leads of the interdigital electrode array from the electrode layer wires, and the electrode layer wires are connected to the interdigital electrode array; S4, applying a second insulating layer; Screen-printing insulating ink on the electrode layer-first insulating layer-electrode layer wire film obtained in S3 to form a second insulating layer to prevent crosstalk, thereby obtaining an electrode layer-first insulating layer-electrode layer wire-second insulating layer film; The second insulating layer covers the flexible substrate, and an array through hole is provided at a position on the second insulating layer facing the interdigital electrode array; S5, coating the spacer layer; Screen-printing a spacer layer ink on the electrode layer-first insulating layer-electrode layer wire-second insulating layer film obtained in S4 to form a spacer layer, thereby obtaining an electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film; The spacer layer includes an outer frame, and spacer bars are arranged in an inner space formed by the outer frame. The spacer bars are located at the gap facing the interdigital electrode array, and the spacer bars include a plurality of segments. S6. preparing a sensitive layer; Select a flexible substrate, screen-print the sensitive layer ink on the flexible substrate, and perform laser etching on the side of the film printed with the sensitive layer ink to obtain a sensitive layer; The sensitive layer is a flexible substrate on which a sensitive area array is arranged, and the sensitive area array is located directly above the interdigital electrode array; S7, sensor array packaging; The electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film prepared in S5 is aligned and bonded with the sensitive layer prepared in S6, and then packaged to obtain a minimum port interdigital sensor array based on screen printing.

2. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S1: The flexible substrate is made of a polyurethane hot melt adhesive film, which is first cleaned in a plasma cleaning machine, and then placed on the platform below the ultraviolet laser machine for vacuum adsorption and then laser etching. After etching is completed, the polyurethane hot melt adhesive film is placed in a plasma cleaning machine to clean the etching residues, thereby obtaining a flexible substrate with a shading structure; The conductive ink is prepared by stirring slow-drying water and conductive silver paste and mixing them evenly; After the conductive ink is screen-printed on the flexible substrate, it is heated and cured to obtain an interdigitated electrode layer; The cleaning time of the plasma cleaning machine was controlled to be 2-3 minutes. The pre-designed vertical grain structure profile was input into the UV laser machine. The UV light power was adjusted to 3-5W, the laser frequency to 60 KHz, the laser pulse width to 10 us, and 9-11 cycles of cutting were performed. The heating and curing temperature was controlled to be 70°C, and the heating and curing time was controlled to be 5-10 minutes.

3. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S2: place the interdigitated electrode layer on the screen printing table, align the first insulating layer screen and place it above the interdigitated electrode layer, invert the drying type insulating ink on the first insulating layer screen, and print it at an angle with a scraper on the overlapping part of the interdigitated electrode leads; then place it on a 70°C heating table and heat it for 5-10 minutes, and after curing, obtain the electrode layer-first insulating layer film.

4. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S3: the conductive ink is prepared by stirring slow-drying water and conductive silver paste and mixing them evenly; the cured electrode layer-first insulating layer film is placed on a screen printing table, the electrode layer wire screen is aligned and placed above the first insulating layer, the conductive ink is inverted on the electrode layer wire screen, and the scraper is tilted to print on the overlapping part of the interdigitated electrode leads; then it is placed on a 70°C heating table and heated for 5-10 minutes to obtain an electrode layer-first insulating layer-electrode layer wire film after curing.

5. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S4: the electrode layer-first insulating layer-electrode layer wire film obtained after curing is placed on the screen printing table, the second insulating layer screen is aligned and placed above the film, the drying type insulating ink is inverted on the second insulating layer screen, and the scraper is tilted for printing; then it is placed on a 70°C heating table and heated for 5-10 minutes, and after curing, the electrode layer-first insulating layer-electrode layer wire-second insulating layer film is obtained.

6. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S5: thermoplastic polyurethane elastomer and N,N-dimethylformamide are mixed and magnetically stirred to obtain spacer layer ink; the electrode layer-first insulating layer-electrode layer wire-second insulating layer film obtained after curing is placed on a screen printing table, the spacer layer screen is aligned and placed above the film, the spacer layer ink is inverted on the spacer layer screen, and the scraper is tilted for printing to obtain electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film.

7. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S6: thermoplastic polyurethane elastomer and N,N-dimethylformamide are mixed, magnetically stirred, and carbon nanotube powder is added under stirring to obtain sensitive layer ink; The flexible substrate is made of a polyurethane hot melt adhesive film, which is cleaned in a plasma cleaner and then preheated on a heating table. The polyurethane hot melt adhesive film is then fixed on a screen printing table, a sensitive layer screen is fixed on top of the film, and the sensitive layer ink is placed upside down on the sensitive layer screen. The film is printed at an angle using a scraper, and after printing is completed, the film is placed on a heating table for heating and curing. Then place the polyurethane hot melt adhesive film on the platform below the UV laser machine, vacuum adsorb it, and perform laser etching; After etching is completed, it is placed in a plasma cleaning machine to clean the etching residues to obtain a sensitive layer; Control the cleaning time of the plasma cleaning machine to 2-3 minutes; the preheating temperature of the heating table is 70°C, and the preheating time is 2-3 minutes; control the heating and curing temperature to 70°C, and the heating and curing time is 5-10 minutes; input the pre-designed vertical grain structure profile into the UV laser machine, adjust the UV light power to 3-5W, the laser frequency to 60 KHz, the laser pulse width to 10 us, and perform 20-25 cycles of cutting.

8. The method for preparing a minimum port interdigital sensor array based on screen printing according to claim 1, characterized in that: In step S7: align and bond the electrode layer-first insulating layer-electrode layer wire-second insulating layer-spacer layer film prepared in S5 with the sensitive layer prepared in S6, place them in a vacuum heating box, evacuate, heat to 100-110°C, and heat at this temperature for 50-60 minutes, and then cool to achieve flexible packaging.

9. A screen-printed minimum port interdigital sensor array prepared by the method of any one of claims 1 to 8, characterized in that: The interdigital sensor array comprises a sensitive layer, a spacer layer, a second insulating layer, an electrode layer wire, a first insulating layer and an interdigital electrode layer stacked in sequence from top to bottom; The interdigitated electrode layer is an integrated structure formed by a first flexible substrate with a first shading structure and an interdigitated electrode array screen-printed thereon; the first insulating layer covers the overlapping portions of the leads of the interdigitated electrode array; the electrode layer wires are arranged above the first insulating layer, and the overlapping portions of the leads of the interdigitated electrode array are separated from the electrode layer wires by the first insulating layer; the electrode layer wires are connected to the interdigitated electrode array; The second insulating layer covers the first flexible substrate, and an array through hole is provided at a position on the second insulating layer facing the interdigital electrode array; The spacer layer includes an outer frame, and spacer bars are arranged at intervals in the inner space formed by the outer frame. The spacer bars are located at the gaps facing the interdigital electrode array, and the spacer bars include a plurality of segments. The sensitive layer includes a second flexible substrate, on which a sensitive area array is arranged. The sensitive area array is located directly above the interdigital electrode array, and a second shading structure is etched on the sensitive area array.

10. The screen-printed minimum port interdigital sensor array according to claim 9, characterized in that: When preparing the interdigital electrode layer, a first shading structure is etched on one side of the first flexible substrate, and an interdigital electrode array is screen-printed on the first shading structure; and the extending direction of the first shading structure is perpendicular to the direction of the interdigital electrodes in the interdigital electrode array; When preparing the sensitive layer, a sensitive area array is screen-printed on one side of the second flexible substrate, and then a second shading structure is etched on the sensitive area array, wherein the extension direction of the second shading structure is the same as that of the first shading structure; When the sensor array is packaged, the second flexible substrate is inverted on top of the first flexible substrate, and the sensitive area array and the interdigital electrode array are arranged facing each other.

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