Flexible sensor capable of resisting signal crosstalk and preparation method thereof

Abstract

The invention discloses an anti-signal-crosstalk flexible sensor and a preparation method thereof. The flexible sensor comprises a first insulating layer, a first conductive shielding layer, a second insulating layer, a sensing array layer, a friction layer and a second conductive shielding layer which are sequentially stacked from bottom to top, the sensing array layer comprises a plurality of sensing units distributed in an array mode, each sensing unit comprises an electrode and a wire, and the electrodes of the adjacent sensing units are spaced by a preset gap; the second conductive shielding layer comprises conductive shielding sections and friction sections, the friction sections and the electrodes are arranged in a one-to-one correspondence mode, and the electrodes are located in the projection range of the friction sections; the wire is located within the projection range of the conductive shielding section. Signal interference between the sensor and the external environment is shielded through the first conductive shielding layer, signal interference between the sensor array and the wire is reduced through the second conductive shielding layer, the error recognition rate of the sensor array is effectively reduced, and the recognition stability of the sensor is improved.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics technology, and in particular to a flexible sensor resistant to signal crosstalk and its fabrication method. Background Technology

[0002] With the rapid development of flexible electronics technology, flexible and stretchable electronic devices have been widely used in wearable devices, intelligent robots, health monitoring, and other fields. However, when flexible electronic devices achieve large-area, high-density integration, signal crosstalk easily occurs between sensor arrays, and signal interference also occurs between wires, leading to a high false recognition rate and seriously affecting the performance and reliability of the sensor array. Traditional anti-interference methods mostly target signal interference between the sensor and the external environment, without considering internal signal interference within the sensor array. Summary of the Invention

[0003] Purpose of the invention: To address the drawback of signal crosstalk between sensor arrays and between wires, this invention provides a flexible sensor resistant to signal crosstalk and its fabrication method. By rationally setting the structure of each layer of the sensor, signal interference between the sensor array and the wires is reduced, thereby improving the stability of the sensor.

[0004] Technical Solution: To solve the above problems, the present invention employs a flexible sensor resistant to signal crosstalk, comprising, from bottom to top, a first insulating layer, a first conductive shielding layer, a second insulating layer, a sensing array layer, a friction layer, and a second conductive shielding layer stacked sequentially; the sensing array layer comprises multiple sensing units arranged in an array, each sensing unit comprising an electrode and a wire, with a predetermined gap between the electrodes of adjacent sensing units; the second conductive shielding layer comprises a conductive shielding section and a friction section, the friction section being arranged one-to-one with the electrode, and the electrode being located within the projection range of the friction section; the wire is located within the projection range of the conductive shielding section.

[0005] Furthermore, the first and second insulating layers are made of flexible insulating material.

[0006] Furthermore, the flexible insulating material is one of silicone, polyurethane, PDMS, and polyacrylate.

[0007] Furthermore, the first conductive shielding layer and conductive shielding segment are made of a hybrid material of conductive functional material and elastomer.

[0008] Furthermore, the conductive functional material is one of silver nanowires, carbon nanotubes, carbon black, graphene, and carbon fiber.

[0009] Furthermore, the friction layer and friction segment are made of one of silicone, polyurethane, PDMS, or polyacrylate.

[0010] The present invention also provides a method for fabricating the above-mentioned flexible sensor resistant to signal crosstalk, providing an overall mold and a sensor array layer mold, including the following steps:

[0011] S1. Prepare the second conductive shielding layer; coat the conductive shielding layer material onto the overall mold, and after the material is cured, cut it into hollow sections according to the shape of the gap between the wire and the adjacent electrode to form a conductive shielding section; pour the friction layer material into the hollow section of the conductive shielding section, and after the material is cured, form a friction section.

[0012] S2. Prepare the friction layer; coat a friction layer material onto the second conductive shielding layer, and the friction layer is formed after the material is cured.

[0013] S3. Prepare the sensor array layer; pour the sensor array layer material into the sensor array layer mold printed with electrode and wire patterns, and after the material is cured, the sensor array layer is formed. Attach the sensor array layer to the friction layer.

[0014] S4. Prepare the second insulating layer; cast insulating material onto the sensor array layer and coat it evenly, then cure to form the second insulating layer;

[0015] S5. Prepare the first conductive shielding layer by coating a layer of conductive shielding material onto the second insulating layer and curing it to form the first conductive shielding layer.

[0016] S6. Prepare the first insulating layer; pour insulating material onto the first conductive shielding layer and coat it evenly, and form the first insulating layer after curing.

[0017] S7. Demold each layer of the structure from the overall mold and flip it over to obtain a flexible sensor.

[0018] Furthermore, the conductive shielding layer material is made of a mixture of conductive functional material and elastomer, and the conductive functional material is one of silver nanowires, carbon nanotubes, carbon black, graphene, and carbon fiber.

[0019] Furthermore, the conductive functional material and the elastomer are mixed at a volume ratio of 1:1.

[0020] Furthermore, the friction layer material and the insulating layer material are selected from silicone, polyurethane, PDMS, and polyacrylate.

[0021] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that it shields the sensor from signal interference with the external environment through the first conductive shielding layer and reduces signal interference between the sensor array and the wires through the second conductive shielding layer, thereby effectively reducing the false recognition rate of the sensor array and improving the sensor recognition stability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the flexible sensor of the present invention;

[0023] Figure 2 Schematic diagram of the principle for the shielding layer to suppress signal crosstalk between adjacent sensing unit wires;

[0024] Figure 3 This diagram illustrates the effectiveness of the shielding layer in resisting signal crosstalk. Detailed Implementation

[0025] like Figure 1 As shown, a flexible sensor resistant to signal crosstalk in this embodiment includes a first insulating layer 1, a first conductive shielding layer 2, a second insulating layer 3, a sensing array layer 4, a friction layer 5, and a second conductive shielding layer 6 stacked sequentially from bottom to top.

[0026] Both the first insulating layer 1 and the second insulating layer 3 are made of flexible insulating materials, such as silicone, polyurethane, PDMS, polyacrylate, etc. In this embodiment, Ecoflex silicone is used, which has excellent tensile strength and flexibility and can withstand large deformations without damage. The first insulating layer 1 is the base layer of the entire sensor structure, and the second insulating layer 3 is used for electrical isolation between the first conductive shielding layer 2 and the sensing array layer 4.

[0027] The first conductive shielding layer 2 is made of a hybrid material of conductive functional material and elastomer. The conductive functional material can be one of silver nanowires, carbon nanotubes, carbon black, graphene, or carbon fiber. In this embodiment, a hybrid material of carbon black and Ecoflex silicone is used. The first conductive shielding layer 2 is used to shield the sensor array from signal interference between it and the external environment.

[0028] The sensing array layer 4 includes multiple sensing units arranged in an array. In this embodiment, the sensing array layer has four sensing units arranged in a 2×2 array. The sensing unit includes electrodes 41 and wires 42, both of which are made of flexible materials. In this embodiment, both the electrodes and wires are made of a mixture of carbon black and Ecoflex silicone.

[0029] The friction layer 5 is located above the sensor array layer 4 and is used to detect external stimuli and generate electrical signals. The friction layer 5 can be made of materials such as silicone, polyurethane, PDMS, or polyacrylate; in this embodiment, Ecoflex silicone is selected.

[0030] The second conductive shielding layer 6 includes a conductive shielding section 61 covering the wire and a friction section 62 covering the electrode. In this embodiment, the material of the conductive shielding section 61 is the same as that of the first conductive shielding layer 2, and the material of the friction section 62 is the same as that of the friction layer 5. Different materials can also be used as long as the same function can be achieved. The conductive shielding section 61 in this embodiment is arranged in a "field" shape, covering the electrode 41 and the gap between adjacent electrodes. The hollow part in the middle of the "field" is the friction section 62, and the friction section 62 covers the electrode 41. The conductive shielding section 61 can absorb and dissipate the stray charges and alternating electromagnetic fields generated by the sensing unit, preventing the induced charges from spreading to adjacent sensing units, thereby significantly reducing the signal crosstalk between sensing units and between wires. And after grounding the conductive shielding section 61, the anti-signal crosstalk performance can be further improved.

[0031] Specifically, the principle of the second conductive shielding layer 6 against signal crosstalk is as Figure 2 shown.

[0032] (1) The mutual inductance principle between adjacent wires without a shielding layer is as follows:

[0033] When an external object (such as a finger) touches or separates the sensing unit, a changing potential difference will be generated inside the unit due to the triboelectric effect, thereby driving the electrons (e⁻) in the wire to flow directionally, forming a transient current signal.

[0034] When the sensing unit 1 is triggered, a changing current will flow through its wire instantaneously. According to Faraday's law of electromagnetic induction, any changing current will generate a changing magnetic field around it. This changing magnetic field will penetrate the wire loop of the adjacent sensing unit 2 that is very close, thereby inducing an interference signal in this loop. Even if only the sensing unit 1 is triggered, an obvious interference signal is also recorded in the circuit of the sensing unit 2.

[0035] (2) The mutual inductance principle between adjacent wires when the second conductive shielding layer is not grounded is as follows:

[0036] When the second conductive shielding layer 6 is not grounded, it is in a "floating" potential state. When an interference magnetic field is generated by the electron flow in the sensing unit 1, eddy currents (electron movement) will also be induced in the shielding layer metal, but the reverse magnetic field generated by this eddy current is not enough to completely cancel the original interference magnetic field. Part of the interference magnetic field will still penetrate the shielding layer and affect the adjacent internal wires, which can play a certain shielding effect but the shielding effect is relatively limited, and the sensor signal will still be interfered. Even if only the sensing unit 1 is triggered, a smaller interference signal is also recorded in the circuit of the sensing unit 2.

[0037] (3) The mutual inductance principle between adjacent wires when the second conductive shielding layer 6 is grounded is as follows:

[0038] When the electron flow in sensing unit 1 generates an interfering magnetic field, eddy currents are induced in the grounded second conductive shielding layer 6. Since grounding provides a low-impedance path, these induced electrons can quickly flow into the ground. According to Lenz's law, this eddy current generates a reverse magnetic field with a similar intensity but opposite direction to the original interfering magnetic field, effectively canceling out most of the interfering magnetic field. As a result, the electrons inside sensing unit 2 do not move due to mutual inductance, ensuring the independence and accuracy of the sensing signal.

[0039] This embodiment also provides a method for fabricating the above-mentioned flexible sensor, including the following steps:

[0040] S1. Preparation of the second conductive shielding layer 6. Silicone and carbon black are mixed at a volume ratio of 1:1 (weight ratio 13.4:1) to prepare a conductive shielding material. This material is coated onto a mold and cured at room temperature for 6 hours. After curing, the material is cut into perforations according to the shape of the gaps between the wires and adjacent electrodes to form conductive shielding sections 61. Ecoflex silicone is poured into the perforations of the conductive shielding sections 61. After curing, friction sections 62 are formed, ultimately obtaining the second conductive shielding layer 6.

[0041] S2. Prepare the friction layer 5. Coat a layer of Ecoflex silicone onto the second conductive shielding layer 6. After the material cures, the friction layer 5 is formed.

[0042] S3. Prepare the sensor array layer 4. Pour the mixture of carbon black and Ecoflex silicone into a sensor array layer mold printed with electrode and wire patterns. After the material is cured, the sensor array layer 4 is formed. Attach the sensor array layer 4 to the friction layer 5.

[0043] S4. Prepare the second insulating layer 3. Cast Ecoflex silicone onto the sensor array layer 4 and coat it evenly. After curing, the second insulating layer 3 is formed.

[0044] S5. Prepare the first conductive shielding layer 2. Coat a layer of carbon black and Ecoflex silicone mixed material on the second insulating layer 3. After curing, the first conductive shielding layer 2 is formed.

[0045] S6. Prepare the first insulating layer 1. Pour Ecoflex silicone onto the first conductive shielding layer 2 and coat it evenly. After curing, the first insulating layer 1 is formed.

[0046] S7. Demold each layer of the structure from the overall mold and flip it over to obtain a flexible sensor.

[0047] To verify the anti-signal crosstalk effect of the flexible sensor of the present invention, the output voltage of the adjacent sensing units was tested when the sensing unit 1 was stimulated in three cases: without the second conductive shielding layer, with the second conductive shielding layer but not grounded, and with the second conductive shielding layer and grounded. The results are as follows: Figure 3The diagram shows the signal interference shielding effect. The dense output voltage lines at the bottom of the diagram represent instrument noise signals, which cannot be avoided in any of the three scenarios. Without a shielding layer, the output voltage of adjacent sensors is significantly interfered with, reaching close to 8V. With a second conductive shielding layer but not grounded, the output voltage of adjacent sensors is also somewhat interfered with, reaching close to 4V, but this is an improvement compared to the case without a shielding layer. With a second conductive shielding layer and grounding, adjacent sensors experience almost no signal interference, only instrument noise signals, demonstrating a significant anti-interference effect.

Claims

1. A flexible sensor resistant to signal crosstalk, characterized in that, The system comprises, from bottom to top, a first insulating layer (1), a first conductive shielding layer (2), a second insulating layer (3), a sensing array layer (4), a friction layer (5), and a second conductive shielding layer (6); the sensing array layer (4) comprises multiple sensing units arranged in an array, each sensing unit comprising an electrode (41) and a wire (42), with a preset gap between the electrodes of adjacent sensing units; the second conductive shielding layer (6) comprises a conductive shielding section (61) and a friction section (62), the friction section (62) being arranged in a one-to-one correspondence with the electrode (41), and the electrode (41) being located within the projection range of the friction section (62); the wire (42) is located within the projection range of the conductive shielding section (61).

2. The flexible sensor against signal crosstalk as described in claim 1, characterized in that, The first insulating layer (1) and the second insulating layer (3) are made of flexible insulating material.

3. The flexible sensor against signal crosstalk as described in claim 2, characterized in that, The flexible insulating material is one of silicone, polyurethane, PDMS, or polyacrylate.

4. The flexible sensor against signal crosstalk as described in claim 1, characterized in that, The first conductive shielding layer (2) and the conductive shielding section (61) are made of a mixture of conductive functional materials and elastomers.

5. The flexible sensor against signal crosstalk as described in claim 4, characterized in that, The conductive functional material is one of silver nanowires, carbon nanotubes, carbon black, graphene, and carbon fiber.

6. The flexible sensor resistant to signal crosstalk as described in claim 1, characterized in that, The friction layer (5) and friction section (62) are made of one of silicone, polyurethane, PDMS and polyacrylate.

7. A method for fabricating a flexible sensor resistant to signal crosstalk as described in any one of claims 1-6, characterized in that, Providing an overall mold and a sensor array layer mold includes the following steps: S1. Prepare the second conductive shielding layer (6); coat the conductive shielding layer material onto the overall mold, and after the material is cured, cut it into hollow sections according to the shape of the gap between the wire and the adjacent electrodes to form a conductive shielding section (61); pour the friction layer material into the hollow section of the conductive shielding section (61), and after the material is cured, form a friction section (62). S2. Prepare the friction layer (5); coat a layer of friction layer material on the second conductive shielding layer (6), and the friction layer (5) is formed after the material is cured. S3. Prepare the sensor array layer (4); pour the sensor array layer material into the sensor array layer mold printed with electrode and wire patterns, and after the material is cured, the sensor array layer (4) is formed. Attach the sensor array layer (4) to the friction layer (5). S4. Prepare the second insulating layer (3); pour the insulating layer material onto the sensing array layer (4) and coat it evenly. After curing, the second insulating layer (3) is formed. S5. Prepare the first conductive shielding layer (2), coat a layer of conductive shielding material on the second insulating layer (3), and cure to form the first conductive shielding layer (2). S6. Prepare the first insulating layer (1); pour insulating material onto the first conductive shielding layer (2) and coat it evenly. After curing, the first insulating layer (1) is formed. S7. Demold each layer of the structure from the overall mold and flip it over to obtain a flexible sensor.

8. The preparation method according to claim 7, characterized in that, The conductive shielding layer material is made of a mixture of conductive functional material and elastomer, and the conductive functional material is one of silver nanowires, carbon nanotubes, carbon black, graphene, and carbon fiber.

9. The preparation method according to claim 8, characterized in that, The conductive functional material and the elastomer are mixed at a volume ratio of 1:

1.

10. The preparation method according to claim 7, characterized in that, The friction layer material and the insulating layer material are selected from silicone, polyurethane, PDMS, and polyacrylate.

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