Low-noise self-powered array pressure sensor, preparation method thereof and signal processing system

Abstract

The invention belongs to the technical field of self-powered pressure sensing, and particularly relates to a low-noise self-powered array pressure sensor, a preparation method thereof and a signal processing system. The array pressure sensor comprises a PCB, and an electrode layer array, an interference shielding layer, a lower friction layer, a spacing layer, an upper friction layer and a pressed layer which are arranged on the PCB. Wherein the electrode layer array is surrounded by the interference shielding layer and isolated from each other, the interference shielding layer is arranged below the lower friction layer, the lower friction layer is arranged below the spacing layer, the spacing layer is arranged below the upper friction layer, and the upper friction layer is arranged below the compression layer. Compared with a dual-electrode triboelectric array, the single-electrode layer array pressure sensor based on triboelectrification has the advantages that the number of wires is reduced by half, the number of IO ports required by a circuit is effectively reduced, and the complexity of a signal processing hardware system is reduced.

Description

Technical Field

[0001] This invention belongs to the field of self-powered pressure sensing technology, specifically relating to a low-noise self-powered array pressure sensor, its fabrication method, and signal processing system. Background Technology

[0002] With the advent of the Internet of Things (IoT) era, self-powered pressure sensors, due to their advantages of requiring no external power source and operating continuously, have shown broad application prospects in personalized medical management, human-computer interaction, smart homes, and environmental monitoring. Traditional sensors rely on external power sources or batteries, which not only limits the miniaturization and flexibility of devices but also increases maintenance costs and environmental burden. Self-powered technology directly converts environmental mechanical energy (such as pressure and vibration) into electrical energy through piezoelectric, triboelectric, or electrochemical mechanisms, achieving energy self-sufficiency, and is particularly suitable for remote or power-difficult scenarios. Triboelectric sensors, with their high sensitivity, low cost, and flexible structure, have become a hot topic in self-powered sensing research.

[0003] To improve the accuracy of spatial pressure distribution detection, sensor structures have gradually evolved from single-unit to array-based designs, with array sizes continuously increasing to achieve high-resolution pressure mapping and meet the multi-point tactile sensing requirements of applications such as artificial skin and intelligent robots. However, the increased array size leads to increasingly complex fabrication processes, involving multi-layer material integration, micro / nano structure fabrication (such as electrospinning and laser etching), and high-density electrode lead layout. Interference can easily occur between adjacent units in the array due to electromagnetic coupling or shared loops. Furthermore, as the number of channels increases, the parasitic capacitance and impedance noise of the signal readout network are amplified, severely limiting the signal-to-noise ratio and measurement accuracy.

[0004] Noise has become a bottleneck restricting the performance improvement of large-scale self-powered array sensors. Especially in triboelectric arrays, the single-electrode structure is susceptible to environmental electromagnetic interference (such as power frequency noise and radio frequency signals), leading to baseline drift or spurious pulses in the output signal, significantly reducing the accuracy and reliability of pressure detection. Existing technologies mostly rely on external metal shielding or complex filtering algorithms, but these increase size and are difficult to integrate. To address this problem, this invention innovatively introduces an interference shielding layer design. By using a closed, irregularly shaped immersion gold pad on the PCB to wrap the lower electrode array and connect it to analog ground, a local electromagnetic isolation zone is formed. This structure effectively suppresses common-mode noise and crosstalk, reducing signal noise by more than an order of magnitude compared to traditional unshielded single-electrode arrays, providing a key foundation for the realization of high-density arrays.

[0005] In signal processing, early array sensors generally relied on commercial signal acquisition cards for data reading. While offering high flexibility, these cards suffered from problems such as large size, poor channel scalability, high cost, and interference from mixed digital-analog signals. This discrete approach struggled to meet the real-time, low-power, and highly integrated requirements of wearable devices. This invention proposes a highly integrated multi-channel signal processing system with built-in modules for analog-to-digital ground isolation and DC bias decoupling. This hardware-level approach avoids noise introduced by signal acquisition cards and, combined with a QT host computer, enables real-time visualization of pressure distribution, significantly improving the system's signal-to-noise ratio and scalability. Summary of the Invention

[0006] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide a low-noise self-powered array pressure sensor, its fabrication method, and signal processing system that meet one or more of the aforementioned requirements.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A low-noise self-powered array pressure sensor includes a PCB board and an electrode layer array, an interference shielding layer, a lower friction layer, a spacer layer, an upper friction layer, and a pressure-bearing layer disposed on the PCB board. The electrode layer array is surrounded and isolated from each other by an interference shielding layer. The interference shielding layer is below the lower friction layer, the lower friction layer is below the spacer layer, the spacer layer is below the upper friction layer, and the upper friction layer is below the pressure layer.

[0008] As a preferred embodiment, the electrode layer array is a conductive electrode array made of irregularly shaped pads on a PCB board. The conductive electrode array includes an array of electrode units, and each electrode unit includes row irregularly shaped pads and column irregularly shaped pads that are mirror-symmetric and isolated from each other.

[0009] As a preferred embodiment, the interference shielding layer is made of a closed, irregularly shaped pad on the PCB.

[0010] As a preferred embodiment, the lower friction layer is a polydimethylsiloxane film, and the upper surface of the lower friction layer is subjected to ICP etching.

[0011] As a preferred embodiment, the spacer layer is a polyimide film with through holes corresponding to the electrode units, and the vertical projection of the through holes covers the corresponding electrode units.

[0012] As a preferred embodiment, the upper friction layer is a polyvinyl alcohol fiber film.

[0013] As a preferred embodiment, the pressure-bearing layer is a polyimide film.

[0014] The present invention also provides a method for fabricating a low-noise self-powered array pressure sensor as described in any of the preceding embodiments, comprising the following steps: S1. Use row and column irregular pads to create an electrode layer array on the PCB board; S2. Use closed irregularly shaped pads to surround the electrode layer array to create an interference shielding layer on the PCB board; S3. A lower friction layer is fabricated on the upper surface of the electrode layer array and the interference shielding layer using a spin coating method and then cured. S4. The upper surface of the lower friction layer is processed by ICP etching to form a microstructure. S5. A double-sided adhesive polyimide film is laser-cut to obtain through holes, forming a spacer layer; S6. Electrospinning is used to prepare a polyvinyl alcohol fiber film on the pressure layer to obtain the upper friction layer; S7. Bond the upper friction layer to the spacer layer.

[0015] The present invention also provides a signal processing system, including a low-noise self-powered array pressure sensor as described in any of the above embodiments or a low-noise self-powered array pressure sensor prepared by the preparation method described in the above embodiments.

[0016] Compared with the prior art, the beneficial effects of this invention are: (1) The single-electrode array pressure sensor based on triboelectricity designed in this invention reduces the number of wires by half compared with the dual-electrode triboelectric array, effectively simplifying the number of I / O ports required by the circuit and reducing the complexity of the signal processing hardware system. (2) This invention utilizes 6-layer PCB through-hole technology to reduce the manufacturing difficulty of the sensor array and introduces a shielding layer for analog connection to greatly improve the signal-to-noise ratio; (3) The upper and lower friction layers of the present invention have been modified with surface morphology, which improves the charge transfer efficiency and effectively enhances the output of triboelectric signal; (4) This invention does not rely on expensive professional multi-channel signal acquisition cards, and the number of channels is easy to expand. It is less affected by the external environment and can work stably in complex environments. (5) The present invention designs a QT host computer adapted to the signal processing circuit, which can display the electrical signal and amplitude of the pressure position in real time. Combined with the analysis module and deep learning algorithm, it can realize practical applications such as real-time self-driven touch imaging, self-driven touch sensor, and self-driven keyboard. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the self-powered array pressure sensor of the present invention; Figure 2 This is a schematic diagram of the lower electrode layer array structure and row and column electrode lead pads of the present invention; Figure 3 This is the waveform of the single-channel single-electrode triboelectric signal of the present invention; Figure 4 This is a SEM image of the polydimethylsiloxane thin film of the upper friction layer after ICP etching according to the present invention; Figure 5 This is a SEM image of the lower friction layer polyvinyl alcohol in the electrospun material of the present invention. Figure 6 These are schematic diagrams and actual images of the spacer layer polyimide after laser cutting according to the present invention; Figure 7 This is a physical image of the self-powered array pressure sensor of the present invention; Figure 8 This is a schematic diagram of the signal processing circuit of the present invention; Figure 9 This is a physical diagram of the signal processing circuit of the present invention; Figure 10 This is a test diagram of the effect of the host computer software of the present invention; Figure 11 This is a schematic diagram of the operation of the self-powered array pressure sensor and signal processing system of the present invention. Detailed Implementation

[0018] To more clearly illustrate the embodiments of the present invention, specific implementation methods will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0019] This invention aims to overcome the crosstalk problem between adjacent units of a self-powered array pressure sensor based on a single-electrode triboelectric nanogenerator, achieving a high signal-to-noise ratio and low noise. Furthermore, a practical 32-channel signal processing circuit with low crosstalk, low noise, and analog-to-digital signal isolation was developed. This overcomes some problems existing in current signal processing methods, such as high cost of signal acquisition cards, complex measurement processes, limited functionality, poor scalability, and limited measurement parameters. It provides a signal processing system with high signal-to-noise ratio, low crosstalk, low noise, high integration, and strong scalability. Adaptive host computer software was also developed, featuring simple measurement methods and strong scalability.

[0020] The low-noise self-powered array pressure sensor of the present invention includes a PCB board and an electrode layer array, an interference shielding layer, a lower friction layer, a spacer layer, and an upper friction layer disposed on the PCB board. The electrode layer array is surrounded by the interference shielding layer and isolated from each other. The interference shielding layer is below the lower friction layer. The lower friction layer is below the spacer layer. The spacer layer is below the upper friction layer. The upper friction layer is below the pressure layer.

[0021] Furthermore, the aforementioned electrode layer array is a conductive electrode array made of irregularly shaped pads on a PCB. The conductive electrode array includes an array of electrode units, and each electrode unit includes row irregularly shaped pads and column irregularly shaped pads that are mirror-symmetric and isolated from each other. Preferably, both the row irregularly shaped pads and the column irregularly shaped pads are semi-circular.

[0022] The aforementioned interference shielding layer is made of a closed, irregularly shaped pad on the PCB.

[0023] The aforementioned lower friction layer is formed by curing polydimethylsiloxane and then etching it using ICP. Specifically, Dow Corning Sylgard 184 is used. The basic components and curing agent are completely mixed at a weight ratio of 10:1. After vacuum degassing, the mixture is spin-coated onto the upper surface of the electrode array and the interference shielding layer. Then, it is cured by heating at 120°C for 2 hours to obtain the lower friction layer. Furthermore, the upper surface of the lower friction layer is surface-processed using ICP etching to form a microstructure and increase the roughness.

[0024] The aforementioned spacer layer is a double-sided adhesive polyimide film, and through holes are obtained by laser cutting. Each through hole corresponds to an electrode unit, and the vertical projection of the through hole covers its corresponding electrode unit.

[0025] The upper friction layer is composed of an electrospun polyvinyl alcohol fiber film; the pressure layer is composed of an adhesive polyimide film. Preferably, the upper friction layer is obtained by electrospinning the adhesive surface of the pressure layer.

[0026] The low-noise self-powered array pressure sensor of the present invention is generated by friction and does not require an external power supply.

[0027] The method for fabricating the low-noise self-powered array pressure sensor of the present invention includes the following steps: S1. Design the electrode layer array structure, shielding layer structure, and electrode layer lead pads using a 6-layer PCB board; specifically, use row-shaped pads and column-shaped pads to create the electrode layer array on the PCB board, and use closed-loop shaped pads to surround the electrode layer array to create an interference shielding layer on the PCB board. S2. A polydimethylsiloxane film with an upper friction layer is prepared using a spin coating-thermal curing method. After complete curing, the surface morphology is etched by ICP to form a microstructure and improve the roughness. S3. A polyimide adhesive film with through holes of a certain size is laser-cut and pasted between the lower friction layer and the upper friction layer to form a closed cavity structure with a certain space, effectively separating polydimethylsiloxane and polyvinyl alcohol; wherein, the vertical projection of the through hole covers its corresponding electrode unit. S4. An upper friction layer is prepared on the pressure layer by electrospinning, which effectively increases its specific surface area, increases the contact area between the upper and lower friction layers, improves the charge transfer efficiency, thereby enhancing the output signal and helping to further improve the signal-to-noise ratio. The signal processing system of the present invention includes: The aforementioned low-noise, self-powered array pressure sensor is used to acquire pressure signals; A modular ground isolation module is used to isolate digital signals from mutual interference with analog signals; The DC bias decoupling module isolates bias signals generated by electromagnetic interference, ensuring the consistency of multiple signals after voltage boost. An interactive module based on a QT host computer is used to realize the real-time display of the position and magnitude of the pressure signal; The analysis module obtains the sensor's pressure location and pressure magnitude by analyzing the generated pulse voltage and amplitude; The row and column signal wires and shielding signal wires led out from the electrode layer array are used to connect to the input port of the signal processing circuit and the analog ground, respectively.

[0028] Example 1: like Figure 1 As shown, the low-noise self-powered array pressure sensor of this embodiment includes electrode layer pads a for leads, a PCB board b for routing, an electrode layer array d, an interference shielding layer c, a lower friction layer e, a spacer layer f, an upper friction layer g, and a pressure-bearing layer h. The electrode layer pads are located on the bottom layer of the PCB board; the PCB board is below the electrode layer array; the electrode layer array is surrounded by the interference shielding layer and is located on the same layer; the interference shielding layer is below the lower friction layer; the lower friction layer is below the spacer layer; the spacer layer is below the upper friction layer; and the upper friction layer is below the pressure-bearing layer.

[0029] Specifically, the electrode layer array consists of semi-circular row and column irregular pads forming a circular pad array on the PCB board. The row and column irregular pads are mirror images of each other and are isolated from each other. The interference shielding layer uses closed irregular immersion gold pads to surround the electrode layer array and isolate them from each other. The lower friction layer is a polydimethylsiloxane film made by spin coating-thermal curing and then in close contact with the electrode layer array after ICP etching. The spacer layer consists of through holes laser-cut from double-sided adhesive polyimide film, which bond the upper and lower friction layers. The upper friction layer is composed of electrospun PVA fiber film. The pressure layer is composed of polyimide film and serves as the support layer for the upper friction layer.

[0030] The working principle of this embodiment is based on a single-electrode triboelectric nanogenerator (SE-TENG). The array pressure sensor mainly relies on row and column scanning to determine the pressing position. It generates output voltages of different amplitudes through the frictional vibration of the upper and lower friction layers and the contact separation process.

[0031] like Figure 2 As shown, corresponding row and column pulse signals will be generated at the pressure position of the array unit.

[0032] like Figure 3 The image shows the pulse signal waveform generated by the array pressure sensor in this embodiment, demonstrating low noise.

[0033] In addition, to improve the triboelectric charge conversion efficiency, the polydimethylsiloxane film of the lower triboelectric layer was subjected to ICP etching, and its SEM image is shown below. Figure 4 As shown, this improves surface roughness.

[0034] The upper friction layer is composed of an electrospun polyvinyl alcohol fiber film, and its SEM image is shown below. Figure 5 As shown.

[0035] Because the upper friction layer of polyvinyl alcohol fiber has the characteristics of high specific area, flexibility and good stability, it can well reflect the magnitude of pressure to the magnitude of the triboelectric signal. The normalized signal has good consistency and can realize the function of pressure mapping.

[0036] like Figure 6 As shown, the spacer layer of the array pressure sensor in this embodiment is formed by laser cutting a through-hole array from a double-sided adhesive polyimide film of a certain thickness, which is used to bond the upper and lower friction layers.

[0037] The method for fabricating the self-powered array pressure sensor in this embodiment includes the following steps: S1, with a 10 cm × 10 cm × 50 μm double-sided adhesive polyimide array of through-holes cut by laser cutting, is shown in the image below. Figure 6 As shown, it serves as a spacer layer and adheres to the upper and lower friction layers; S2, a polyvinyl alcohol fiber film with an upper friction layer was fabricated using electrospinning. The spinning solution had the following mass percentage composition: polyvinyl alcohol powder: Triton-X100: citric acid granules: deionized water = 13:0.75:5:81.25. The specific steps were as follows: Triton-X100 and polyvinyl alcohol powder were added to deionized water, and the solution was heated in a water bath at 80°C with magnetic stirring for 2 hours to obtain a colorless and clear solution. Citric acid granules were then added, and the solution was stirred for another hour at 80°C. After naturally cooling to room temperature, the solution was defoamed using a vacuum pump to obtain the spinning solution. The key spinning parameters were: a 10 cm × 10 cm × 20 μm polyimide film support layer as the receiving substrate, a spinning voltage of 25 kV, a needle distance of 8 cm, and an injection speed of 0.5 mL / h. S3, a spacer layer is bonded above the lower friction layer (polydimethylsiloxane), and a friction layer is bonded above the spacer layer, forming a closed cavity structure with a certain space, effectively separating the upper and lower friction layers. For example... Figure 7The image shown is a physical diagram of the self-powered array pressure sensor of the present invention.

[0038] The signal processing system of this embodiment includes: A self-powered array pressure sensor is used to acquire pressure signals; The analog-to-digital ground isolation module is used to isolate the mutual interference between digital and analog signals and reduce the interference of the digital signal ground plane on sensitive analog signals. The DC bias decoupling module isolates bias signals generated by electromagnetic interference, ensuring the consistency of multiple signals after voltage boost, which facilitates calculations by the analysis module. An interactive module based on a QT host computer is used to realize the real-time display of the position and magnitude of the pressure signal; The analysis module obtains the sensor's pressure location and pressure magnitude by analyzing the generated pulse voltage and amplitude; Furthermore, the signal processing system also includes row and column signal wires and shielding layer signal wires led out from the lower electrode layer array, which are used to connect to the input port of the signal processing circuit and the analog ground, respectively.

[0039] like Figures 8 to 10 As shown, the assembly method of the signal processing system for a low-noise self-powered array pressure sensor includes the following steps: The row and column electrode leads are led out from the bottom pads of the PCB and connected to the multi-channel signal input port of the signal processing board; the shielding layer signal leads are connected to the analog ground. The signal processing circuit processes the triboelectric pulse signal through the analysis module, determines the pressure location by scanning rows and columns, and determines the pressure magnitude by the amplitude of the voltage pulse. Connect to the host computer via serial port for real-time multi-channel signal and pressure mapping; Figure 9 for Figure 8 A physical diagram of the signal processing circuit, showing how the system is assembled via signal leads and serial port connections.

[0040] Figure 10 This is a test diagram of the effect of the host computer software in this invention, which can display the pressure position and pressure magnitude in real time, and realize the trajectory detection effect with pressure mapping; like Figure 11 As shown, the working process of the signal processing system in this embodiment is as follows: The self-powered array pressure sensor collects multi-point triboelectric pulse signals. The collected data is transmitted to the hardware circuit module via a serial port. The hardware circuit module processes the data through analysis algorithms and displays the calculated data in real time through the host computer interface. Users can obtain the pressure position and force magnitude of the self-powered array pressure sensor in real time.

[0041] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. A low noise self-powered array pressure sensor, characterized in that, The PCB board and the electrode layer array, the interference shielding layer, the lower friction layer, the spacing layer, the upper friction layer and the pressure receiving layer are arranged on the PCB board. The electrode layer array is surrounded by the interference shielding layer and is isolated from each other, the interference shielding layer is below the lower friction layer, the lower friction layer is below the spacing layer, the spacing layer is below the upper friction layer, and the upper friction layer is below the pressure receiving layer.

2. The low noise self-powered array pressure sensor of claim 1, wherein, The electrode layer array is an array of conductive electrodes made of special-shaped pads on the PCB board, and the array of conductive electrodes includes arrayed electrode units, and the electrode units include row special-shaped pads and column special-shaped pads which are mirror-symmetric to each other and isolated from each other.

3. The low noise, self-powered array pressure sensor of claim 2, wherein, The interference shielding layer is made of a piece of closed special-shaped pad on the PCB.

4. The low noise, self-powered array pressure sensor of claim 1, wherein, The lower friction layer is a polydimethylsiloxane film, and the upper surface of the lower friction layer is etched by ICP.

5. The low noise, self-powered array pressure sensor of claim 1, wherein, The spacing layer is a polyimide film, and the spacing layer has a through hole corresponding to each electrode unit, and the vertical projection of the through hole covers the corresponding electrode unit.

6. The low noise, self-powered array pressure sensor of claim 1, wherein, The upper friction layer is a polyvinyl alcohol fiber film.

7. The low noise, self-powered array pressure sensor of claim 1, wherein, The pressure receiving layer is a polyimide film.

8. The method of claim 1-7, wherein the low noise self-powered array pressure sensor is prepared by, The method comprises the following steps: S1, using row special-shaped pads and column special-shaped pads to make an electrode layer array on a PCB board; S2, using a closed special-shaped pad to surround the electrode layer array to make an interference shielding layer on the PCB board; S3, using a spin coating method to make a lower friction layer on the upper surface of the electrode layer array and the interference shielding layer and solidify; S4, using an ICP etching process to process the surface of the upper surface of the lower friction layer to form a microstructure; S5, using laser cutting to obtain a through hole in the double-sided adhesive polyimide film to form a spacing layer; S6, using electrospinning to make a polyvinyl alcohol fiber film on the pressure receiving layer to obtain an upper friction layer; S7, bonding the upper friction layer and the spacing layer.

9. A signal processing system, characterized by The low-noise self-powered array pressure sensor prepared by the method of any one of claims 1-7 or the preparation method of claim 8.

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