A flexible isolated sensor array and method of manufacturing the same

Abstract

This invention discloses a flexible isolated sensing array and its manufacturing method, comprising a flexible sensing substrate, an electrode array, and a flexible protective film. The electrode array includes a lateral conductive film, a longitudinal conductive film, a resistor array, and a flexible substrate; the flexible protective film includes an upper flexible protective film and a lower flexible protective film. The lower surface of the flexible sensing substrate has recessed microstructures. The surfaces of the recessed areas of the microstructures have conductive layers, while the edges of the microstructures are non-conductive, thus the recessed microstructures are electrically isolated from each other. The lateral conductive film, the longitudinal conductive film, and the resistor array are all adhered to the flexible substrate, with the lateral and longitudinal conductive films staggered and passing through the resistor array. The lower surface of the flexible sensing substrate is in contact with the upper surface of the resistor array. This flexible isolated sensing array provides stable signals without crosstalk, has a simple fabrication process, can be fabricated on a large area, and is easily promoted in industry.

Description

Technical Field

[0001] This invention relates to flexible sensing technology, specifically to a flexible isolated sensing array and its manufacturing method. Background Technology

[0002] In practical applications, flexible tactile sensors need to simultaneously monitor contact signals at multiple pressure points. Therefore, they are often fabricated in array form. A typical array fabrication method involves forming lines or island-like patterns on the upper and lower electrodes. When pressure is applied to the sensing array, the magnitude and location of the applied pressure can be detected by comparing the output signals of each sensing unit. However, designs based on rows and columns of electrodes can cause crosstalk between adjacent sensing units.

[0003] Since crosstalk between sensing units inevitably reduces the detection accuracy of tactile sensors, various techniques have been proposed to mitigate its effects. For example, using an active matrix to post-process the signals from the tactile sensor array effectively eliminates crosstalk, but this requires complex circuitry and a large number of electronic components. Geometric design can also reduce crosstalk, such as manually connecting internally perforated sensing units to electrodes to form an array configuration, effectively eliminating electrical crosstalk by electrically isolating the sensing units; however, generating large-scale arrays requires significant effort. Inserting grooves into the sensing material minimizes crosstalk between adjacent sensing units; however, the sensing units are still electrically connected, resulting in a small amount of leakage. Therefore, producing large-area, crosstalk-free tactile sensor arrays using scalable and low-cost manufacturing methods remains challenging. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the purpose of this invention is to provide a flexible isolated sensing array with stable signals and no crosstalk.

[0005] Another objective of this invention is to provide a method for manufacturing a flexible isolated sensor array, so as to realize the large-area manufacturing of sensor arrays.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A flexible isolated sensing array includes a flexible sensing substrate, an electrode array, and a flexible protective film. The electrode array includes a lateral conductive film, a longitudinal conductive film, a resistive block array, and a flexible substrate. The flexible protective film includes an upper flexible protective film and a lower flexible protective film. The lower surface of the flexible sensing substrate has recessed microstructures. The surfaces of the recessed areas of the microstructures have conductive layers, while the edges of the microstructures are non-conductive, thus the recessed microstructures are electrically isolated from each other. The lateral conductive film, the longitudinal conductive film, and the resistive block array are all adhered to the flexible substrate. The lateral and longitudinal conductive films are staggered and pass through the resistive block array. The lower surface of the flexible sensing substrate is in contact with the upper surface of the resistive block array. The upper and lower flexible protective films are respectively attached to the upper surface of the flexible sensing substrate and the lower surface of the flexible substrate. The corresponding areas of the resistive blocks on the lower surface of the flexible sensing substrate form a sensing unit.

[0008] The working principle of the flexible isolated sensing array of this invention is as follows. When the flexible isolated sensing array is not under pressure, the non-conductive edges of the recessed microstructures of the flexible sensing substrate are in contact with the resistive block array. At this time, the resistance of the sensing unit is the resistance of a single resistive block, so the initial resistance of the sensing unit is relatively stable. When the sensing unit of the sensing array is subjected to pressure, the conductive recessed area of ​​the microstructure deforms and begins to contact the resistive block, causing part of the resistance of the microstructure recessed area to be incorporated into the resistive block; the contact area increases with the increase of pressure, thereby reducing the resistance value of the sensing unit. The recessed microstructures are electrically isolated from each other, which means that adjacent sensing units on the sensing array are also electrically isolated, that is, there is no leakage between sensing units, and therefore no crosstalk occurs between adjacent sensing units.

[0009] As a preferred option, the shape of the recessed microstructure features is a pyramid, cone, hemisphere, tetrahedron, or bowl.

[0010] As a preferred option, the flexible substrate, the upper flexible protective film, and the lower flexible protective film are made of flexible, heat-resistant, and corrosion-resistant films. Preferably, the flexible, heat-resistant, and corrosion-resistant film material is polyimide, polyethylene terephthalate, polyethylene, or polypropylene.

[0011] As a preferred option, the sensing units of the flexible isolated sensing array exhibit very small ranges and standard deviations of resistance under both unpressurized and pressurized conditions, demonstrating good signal stability.

[0012] As a preferred option, the absence of crosstalk between sensing units allows the flexible isolated sensing array to accurately identify the shape of an object.

[0013] As a preferred option, the fabrication process of flexible sensing substrates and electrode arrays is simple and easy to operate, and can achieve batch and large-area fabrication.

[0014] A method for manufacturing a flexible isolated sensor array includes the fabrication of a flexible sensor substrate and the fabrication of an electrode array.

[0015] As a preferred option, the manufacturing process of the flexible sensing substrate includes the following steps: (1) Using a template with convex microstructures on the surface, a flexible substrate with concave microstructures on the surface is prepared by injection compression molding, molding, roll forming, spin coating curing or ultraviolet curing process; (2) A conductive layer is formed on the surface of the microstructure by ion sputtering, deposition or spraying process, and then the conductive layer on the edge of the microstructure is removed to make the concave areas of the microstructure electrically isolated from each other, so as to obtain the flexible sensing substrate.

[0016] As a preferred embodiment, the flexible substrate in step (1) is made of polyurethane elastomer, ethylene-octene copolymer, polydimethylsiloxane, polyurethane acrylate, silicone rubber, or photosensitive resin. The conductive layer in step (2) is made of conductive metal, polypyrrole, carbon nanotubes, graphene, or transition metal carbides.

[0017] As a preferred embodiment, the manufacturing process of the electrode array includes the following steps: (1) A mask is adhered to a flexible substrate, and n transverse elongated holes are formed on the mask. After printing and drying conductive silver paste, the mask is removed to obtain n transverse conductive films on the flexible substrate; (2) A mask is adhered to the flexible substrate obtained in step (1), and n×n square or round holes are formed on the mask. The square or round holes overlap on the transverse conductive films. After printing and drying colloidal graphite, the mask is removed to obtain the lower half of the resistor block array on the flexible substrate; (3) The mask used in step (1) is rotated 90° and adhered to the flexible substrate obtained in step (2). After printing and drying conductive silver paste, the mask is removed to obtain n longitudinal conductive films on the flexible substrate; (4) A mask used in step (2) is adhered to the flexible substrate obtained in step (3), and the square or round holes of the mask overlap on the longitudinal conductive films. After printing and drying colloidal graphite, the mask is removed to obtain the upper half of the resistor block array.

[0018] The present invention has the following advantages over the prior art:

[0019] (1) The special isolation structure in this invention makes the signal collected by the sensor array stable, and there is no crosstalk between the sensor units. The pressure sensor can realize the function of multi-point real-time measurement of pressure distribution without the need for amplifiers or other signal processing circuits.

[0020] (2) The fabrication process of the flexible sensing substrate and electrode array in this invention is simple and easy to operate, and can be batch and large-area fabrication. It is easy to promote in industry and has broad application prospects. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the packaging structure of the flexible isolated sensor array of the present invention.

[0022] Figure 2a and Figure 2b This is a schematic diagram of the electrode array in the flexible isolated sensing array of the present invention.

[0023] Figure 3 This is a schematic diagram illustrating the working principle of the flexible isolation sensor array of the present invention.

[0024] Figure 4a and Figure 4b The images are scanning electron microscope (SEM) images, respectively, showing the top view and the 45-degree side view of the surface of the flexible polyurethane elastomer (TPU) sensing substrate with inverted micro pyramids, corresponding to Example 1.

[0025] Figure 5 The curves show the resistance of the sensing unit of the flexible isolated sensing array of the present invention changing over time when it is not under pressure (0 kPa) and under pressure (10 kPa), corresponding to Embodiment 1.

[0026] Figure 6a , Figure 6b and Figure 6c The test results show that there is no crosstalk between adjacent sensing units of the flexible isolated sensing array of the present invention, corresponding to Embodiment 1.

[0027] Figure 7 The relative resistance change of each sensing unit when a key is placed on the flexible isolated sensing array of the present invention corresponds to Embodiment 2.

[0028] The symbols in the above figures are explained as follows: 1—Flexible sensing substrate; 2—Electrode array; 2.1—Transverse conductive film; 2.2—Vertical conductive film; 2.3—Resistor block array; 2.4—Flexible substrate; 3—Flexible protective film; 3.1—Upper flexible protective film; 3.2—Lower flexible protective film. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0030] Figure 1 The packaging structure of the flexible isolated sensing array of the present invention is shown. The flexible isolated sensing array includes a flexible sensing substrate 1, an electrode array 2, and a flexible protective film 3. The electrode array 2 includes a lateral conductive film 2.1, a longitudinal conductive film 2.2, a resistor block array 2.3, and a flexible substrate 2.4 (see...). Figure 2a and 2bThe flexible protective film includes an upper flexible protective film 3.1 and a lower flexible protective film 3.2. The lower surface of the flexible sensing substrate 1 has recessed microstructures. The surface of the recessed areas of the microstructures has a conductive layer, and the edges of the microstructures are non-conductive, thus the recessed microstructures are electrically isolated from each other. The transverse conductive film 2.1, the longitudinal conductive film 2.2, and the resistor array 2.3 are all adhered to the flexible substrate 2.4. The transverse conductive film 2.1 and the longitudinal conductive film 2.2 are staggered vertically and pass through the resistor array 2.3. The lower surface of the flexible sensing substrate 1 is in contact with the upper surface of the resistor array 2.3, and the upper flexible protective film 3.1 and the lower flexible protective film 3.2 are respectively attached to the upper surface of the flexible sensing substrate 1 and the lower surface of the flexible substrate 2.4.

[0031] Figure 3 The working principle of the flexible isolated sensing array of the present invention is illustrated. When the flexible isolated sensing array is not under pressure, the non-conductive edges of the recessed microstructures of the flexible sensing substrate 1 are in contact with the resistive block array 2.3. At this time, the resistance of the sensing unit is the resistance of a single resistive block, so the initial resistance of the sensing unit is relatively stable. When the sensing unit of the sensing array is subjected to pressure, the conductive recessed area of ​​the microstructure deforms and begins to contact the resistive block, causing part of the resistance of the microstructure recessed area to be incorporated into the resistive block; the contact area increases with the increase of pressure, thereby reducing the resistance value of the sensing unit (measured by the transverse conductive film 2.1 and the longitudinal conductive film 2.2). The recessed microstructures are electrically isolated from each other, which means that adjacent sensing units on the sensing array are also electrically isolated, i.e., there is no leakage between sensing units, and therefore no crosstalk occurs between adjacent sensing units.

[0032] Example 1

[0033] In this embodiment, the flexible sensing substrate 1 is made of TPU and has dimensions of 30mm × 30mm × 0.5mm. Its surface is formed with inverted micro-pyramids (such as...). Figure 4a and Figure 4b As shown), the depth, cone angle, and edge width of the inverted micro-pyramid are 50 μm, 60°, and 5 μm, respectively. The manufacturing process of the flexible sensing substrate 1 includes the following steps: (1) A flexible TPU substrate with an inverted micro-pyramid on the surface is prepared by injection compression molding technology; (2) A gold layer with a thickness of about 15 nm is sputtered onto the surface of the TPU substrate with the inverted micro-pyramid to obtain a flexible TPU substrate with a conductive surface; (3) The surface of the flexible TPU substrate with the inverted micro-pyramid is polished with sandpaper to remove the gold layer on the edge of the inverted micro-pyramid to obtain the flexible sensing substrate 1.

[0034] The manufacturing process of electrode array 2 includes the following steps: (1) A mask with a thickness of 0.1 mm is adhered to a flexible substrate 2.4 (PET sheet). The mask has three transverse elongated holes. After printing and drying conductive silver paste, the mask is removed, resulting in three transverse conductive films 2.1 on the flexible substrate 2.4; (2) A mask with a thickness of 0.5 mm is adhered to the flexible substrate obtained in step (1). The mask has 3×3 square holes, which overlap the transverse conductive films 2.1. After printing and drying colloidal graphite, the mask is removed, resulting in three transverse conductive films 2.1 on the flexible substrate 2.4. (2) Obtain the lower half of the resistor block array 2.3; (3) Rotate the mask used in step (1) by 90° and adhere it to the flexible substrate obtained in step (2). After printing and drying the conductive silver paste, remove the mask and obtain 3 longitudinal conductive films 2.2 on the flexible substrate 2.4; (4) Adhere a layer of the mask used in step (2) to the flexible substrate obtained in step (3). The square holes of the mask overlap on the longitudinal conductive films 2.2. After printing and drying the colloidal graphite, remove the mask and obtain the upper half of the resistor block array 2.3.

[0035] Figure 5 The resistance curves of the sensing unit of the flexible isolated sensing array in this embodiment under no pressure (0 kPa) and under pressure (10 kPa) are shown as a function of time. It can be seen that the range and standard deviation of the sensing unit resistance are very small in both states, exhibiting good signal stability.

[0036] Figure 6 shows the test results of no crosstalk between adjacent sensing units of the flexible isolated sensing array in this embodiment. Figure 6a In the process, a weight (mass of 2g, the same below) is placed on the sensing unit (X2, Y2); Figure 6b In the middle, place a weight on each of the two adjacent sensing units ((X2,Y1) and (X2,Y2)) in the same row; Figure 6c In the diagram, a weight is placed on each of the three diagonal sensing units ((X1, Y1), (X2, Y2), and (X3, Y3)). It can be seen that in all three cases, the relative resistance change (ΔR / R0) of the sensing unit with the weight is almost the same (0.013 ± 0.001), while the ΔR / R0 of the sensing unit without the weight is 0, indicating that no crosstalk occurs between adjacent sensing units in the flexible isolated sensing array.

[0037] Example 2

[0038] The manufacturing process of the flexible sensing substrate 1 in this embodiment includes the following steps: (1) A flexible TPU substrate with inverted micro pyramids on the surface is prepared by injection compression molding technology; (2) A two-component commercial polydimethylsiloxane (PDMS) is mixed evenly and then spin-coated onto a glass slide to form a PDMS film with a thickness of about 5 μm; (3) The surface of the flexible TPU substrate with inverted micro pyramids is attached to the PDMS film, and the substrate is placed on a hot plate to cure the PDMS film, forming a PDMS cured film layer on the edges of the inverted micro pyramids on the surface of the TPU substrate, and the glass slide is removed; (4) A conductive polypyrrole (PPy) film layer with a thickness of about 15 nm is deposited on the surface of the TPU substrate with inverted micro pyramids, and the PDMS cured film layer is peeled off to obtain the flexible sensing substrate 1. The parts not mentioned are the same as in Embodiment 1.

[0039] When a key is placed on the flexible isolated sensing array in this embodiment, the ΔR / R0 of each sensing unit is as follows: Figure 7 As shown, the ΔR / R0 of the six sensing units completely covered by the key is almost identical (0.023 ± 0.001), the ΔR / R0 of the partially covered sensing unit is slightly smaller (0.020), and the ΔR / R0 of the two uncovered sensing units is 0. The results indicate that the crosstalk-free characteristic between sensing units allows the flexible isolated sensing array to accurately identify the shape of objects.

[0040] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A flexible isolated sensing array, characterized in that, It includes a flexible sensing substrate, an electrode array, and a flexible protective film; the electrode array includes a transverse conductive film, a longitudinal conductive film, a resistive block array, and a flexible substrate; the flexible protective film includes an upper flexible protective film and a lower flexible protective film; The lower surface of the flexible sensing substrate is provided with recessed microstructures. The surface of the recessed area of ​​the microstructure has a conductive layer, and the edges of the microstructure are non-conductive. Therefore, the recessed microstructures are electrically isolated from each other. The transverse conductive film, the longitudinal conductive film and the resistive block array are all adhered to the flexible substrate. The transverse conductive film and the longitudinal conductive film are staggered and pass through the resistive block array. The lower surface of the flexible sensing substrate contacts the upper surface of the resistive block array to form a sensing unit array. The upper flexible protective film and the lower flexible protective film are respectively attached to the upper surface of the flexible sensing substrate and the lower surface of the flexible substrate. The corresponding area of ​​the resistive block contacts the lower surface of the flexible sensing substrate to form a sensing unit. The working principle of the flexible isolation sensor array is as follows: When the flexible isolation sensor array is not under pressure, the non-conductive edges of the recessed microstructure of the flexible sensing substrate are in contact with the resistive block array. At this time, the resistance value of the sensing unit is the resistance value of a single resistive block, so the initial resistance of the sensing unit is relatively stable. When the sensing units of the sensing array are subjected to pressure, the conductive recessed areas of the microstructures deform and begin to contact the resistive block, causing part of the resistance of the microstructure recessed areas to be incorporated into the resistive block; the contact area increases with increasing pressure, thereby reducing the resistance value of the sensing unit; the recessed microstructures are electrically isolated from each other, which means that adjacent sensing units on the sensing array are also electrically isolated, that is, there will be no leakage between sensing units, and thus no crosstalk between adjacent sensing units.

2. The flexible isolated sensing array according to claim 1, characterized in that, The shapes of the concave microstructure features are pyramids, cones, hemispheres, tetrahedrons, or bowls.

3. The flexible isolated sensing array according to claim 1, characterized in that, The flexible substrate, upper flexible protective film, and lower flexible protective film are made of flexible, heat-resistant, and corrosion-resistant thin films.

4. The flexible isolated sensing array according to claim 3, characterized in that, Flexible, heat-resistant, and corrosion-resistant film materials include polyimide, polyethylene terephthalate, polyethylene, or polypropylene.

5. A flexible isolated sensing array according to any one of claims 1 to 3, characterized in that, The range and standard deviation of the sensing unit resistance of the flexible isolated sensing array are very small under both unstressed and stressed conditions, demonstrating good signal stability.

6. A flexible isolated sensing array according to any one of claims 1 to 3, characterized in that, The crosstalk-free nature of the sensing units enables the flexible isolated sensing array to accurately identify the shape of objects.

7. A flexible isolated sensing array according to any one of claims 1 to 3, characterized in that, The fabrication process of flexible sensing substrates and electrode arrays is simple and easy to operate, and can achieve batch and large-area fabrication.

8. The method for manufacturing a flexible isolated sensing array according to any one of claims 1 to 7, characterized in that, The manufacturing process of flexible sensing substrate includes the following steps: (1) Using a template with a raised microstructure on the surface, a flexible polymer material substrate with a concave microstructure on the surface is prepared by injection compression molding, molding, roll forming, spin coating curing or ultraviolet curing process; (2) A conductive layer is formed on the surface of the microstructure by ion sputtering, deposition or spraying process, and then the conductive layer on the edge of the microstructure is removed so that the concave areas of the microstructure are electrically isolated from each other, and a flexible sensing substrate is obtained.

9. The method for manufacturing a flexible isolated sensing array according to claim 8, characterized in that, In step (1), the flexible substrate is made of polyurethane elastomer, ethylene-octene copolymer, polydimethylsiloxane, polyurethane acrylate, silicone rubber or photosensitive resin; in step (2), the conductive layer is made of conductive metal, polypyrrole, carbon nanotube, graphene or transition metal carbide.

10. A method for manufacturing a flexible isolated sensing array according to any one of claims 1 to 7, characterized in that, The manufacturing process of the electrode array includes the following steps: (1) Adhere a mask to a flexible substrate, and open the mask. n A transverse, narrow aperture is formed by printing and drying conductive silver paste, followed by removal of the mask, resulting in a flexible substrate. n A transverse conductive film; (2) A mask is adhered to the flexible film obtained in step (1), and openings are made on the mask. n × n A square or round hole is placed on top of a transverse conductive film. After printing and drying colloidal graphite, the mask is removed to obtain the lower half of the resistor block array on a flexible substrate. (3) The mask used in step (1) is rotated 90° and adhered to the flexible substrate obtained in step (2). After printing and drying conductive silver paste, the mask is removed to obtain the lower half of the resistor block array on a flexible substrate. n Longitudinal conductive film; (4) Adhere a layer of the mask used in step (2) onto the flexible film obtained in step (3). The square or round holes of the mask overlap on the longitudinal conductive film. After printing and drying the colloidal graphite, remove the mask to obtain the upper half of the resistor block array.

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