A moisture-driven self-powered flexible tactile sensor and preparation method thereof

Abstract

The present invention discloses a moisture-driven self-powered flexible tactile sensor and a preparation method thereof. It is mainly composed of a first flexible substrate, a pressure-sensitive layer, a second flexible substrate, a moisture power generation layer and a breathable protective layer which are stacked in sequence from bottom to top; electrodes are provided at both ends of the moisture power generation layer, and the electrodes at both ends are led out through wires; both ends of the pressure-sensitive layer are led out through wires; the moisture power generation layer is obtained by gradiently depositing a polydopamine hydrophilic layer on the surface through an oxidative polymerization reaction. The tactile sensor of the present invention has good flexibility, is easy to attach to complex surfaces for use, and has self-powered characteristics, can operate independently without an external power supply, has excellent moisture power generation performance, can detect two tactile signals, humidity and pressure, at the same time, and humidity detection and self-power generation are carried out simultaneously, which is conducive to improving the integration of the device.

Description

Technical Field

[0001] The present invention relates to a self-powered tactile sensor and a preparation method thereof, and in particular to a moisture-driven self-powered flexible tactile sensor and a preparation method thereof. Background Art

[0002] Flexible pressure sensors can provide solutions for the interaction between machines and the surrounding environment by mimicking the functions of human skin, and are expected to be used in many fields such as human-computer interaction, intelligent robots, and health monitoring. They are an important part of the current flexible sensor field. In order to expand the application scope of flexible tactile sensors, in addition to improving the sensing performance, it is also necessary to give tactile sensors the ability to operate independently. Especially for implantable or embedded devices, the sustainable operation of sensors is essential. However, traditional tactile sensors are almost all powered by rigid batteries with limited lifespans, which require frequent charging and replacement. At the same time, the weight and volume of the battery itself also hinder the integration of sensor devices, greatly limiting the availability and portability of the device. Therefore, the study of self-powered tactile sensor devices is of great significance to the development and application expansion of tactile sensors.

[0003] The existing self-generating materials and devices are mainly realized through piezoelectric, triboelectric, thermoelectric, photovoltaic and wet gas power generation. Compared with other power generation methods, the advantage of wet gas power generation is that it has stronger environmental adaptability. It has a certain power generation capacity even in arid areas with low humidity, and does not require mechanical movement, light or heat as energy sources. It can directly generate electricity using water vapor resources that are ubiquitous in nature. At the same time, humidity is one of the main detection parameters of tactile sensors. Wet gas power generation can realize humidity detection and self-generation simultaneously, which is conducive to improving device integration. Therefore, it is of great significance to develop moisture-driven self-powered flexible tactile sensors. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a moisture-driven self-powered flexible tactile sensor and a preparation method, so as to give the tactile sensor the ability to operate independently.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] 1. A moisture-driven self-powered flexible tactile sensor:

[0007] It is mainly composed of a first flexible substrate, a pressure-sensitive layer, a second flexible substrate, a moisture power generation layer and a breathable protective layer which are stacked in sequence from bottom to top; the pressure-sensitive layer is arranged on the first flexible substrate, and the moisture power generation layer is arranged on the second flexible substrate; electrodes are provided on both ends of the moisture power generation layer, and the electrodes at both ends are connected to an external electrical receiving element through wires, and the electrical receiving element is usually a signal receiver and a tactile sensor; both ends of the pressure-sensitive layer are connected to an external signal receiver through wires.

[0008] The moisture power generation layer adopts a carbon nanofiber membrane modified by polydopamine, and has a water absorption capacity gradient inside.

[0009] The moisture power generation layer is provided with an electrode at both ends along the gradient direction.

[0010] The electrodes are arranged on the upper surface or side surface of the moisture power generation layer, or embedded in the moisture power generation layer.

[0011] The polydopamine content is high at one end of the moisture power generation layer and low at the other end, with a gradient change from one end to the other. Therefore, an electrode is arranged at the end with high polydopamine content and an electrode is arranged at the other end with low polydopamine content.

[0012] The pressure sensitive layer is made of pressure sensitive film material.

[0013] The breathable protective layer is made of porous breathable film material.

[0014] A microstructure is arranged on the upper surface of the pressure sensitive layer.

[0015] The moisture power generation layer is prepared by modifying dopamine in the following manner:

[0016] The polymer nanofiber membrane is first prepared by electrostatic spinning, and then the polymer nanofiber membrane is carbonized at high temperature to obtain a carbon nanofiber membrane; the high temperature is in the range of 400-800°C.

[0017] The carbon nanofiber membrane is immersed in a dopamine solution, and a polydopamine hydrophilic layer is deposited on the fiber surface by oxidative polymerization reaction to obtain a polydopamine-modified fiber membrane with a water absorption capacity gradient as a moisture power generation material.

[0018] During the electrospinning preparation process, the process parameters are adjusted to control the diameter of the fibers in the polymer nanofiber membrane to be 200-5000nm, and the thickness of the polymer nanofiber membrane to be in the range of 5-10μm.

[0019] 2. A method for preparing a self-powered flexible tactile sensor:

[0020] The preparation method comprises:

[0021] S1, attaching a pressure sensitive layer on the first flexible substrate, connecting two ends of the pressure sensitive layer to wires, and attaching a second flexible substrate on top of the pressure sensitive layer;

[0022] S2. Modifying polymer nanofiber membrane using dopamine to obtain wet gas power generation material;

[0023] S3, preparing electrodes at both ends of the moisture power generation material along the gradient direction by means of micro-nano processing technology, connecting the electrodes at both ends to an external load to obtain a moisture power generation layer, and adhering the moisture power generation layer to a second flexible substrate;

[0024] S4. Cover the moisture power generation layer with a layer of porous mesh film material as a breathable protective layer to obtain a self-powered tactile sensor with moisture power generation function.

[0025] The pressure sensitive layer is a pressure sensitive layer with a microstructure on the upper surface, that is, the pressure sensitive layer is pre-processed with a microstructure and then attached to the substrate.

[0026] The moisture power generation layer of the present invention is obtained by gradiently depositing a polydopamine hydrophilic layer on the surface through an oxidative polymerization reaction, thereby bringing about good moisture power generation performance.

[0027] The beneficial effects of the present invention are:

[0028] The tactile sensor of the present invention has good flexibility and is convenient for being attached to a complex surface for use; the tactile sensor of the present invention has a self-powered characteristic and can operate independently without an external power supply.

[0029] The present invention has excellent moisture power generation performance and has a certain power generation capacity even in arid areas with low humidity. It does not require mechanical movement, light or heat as an energy source and has strong environmental adaptability. The tactile sensor of the present invention can simultaneously detect two tactile signals, humidity and pressure. Humidity detection and self-generation are carried out simultaneously without interfering with each other, which is conducive to improving device integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the self-powered tactile sensor of the present invention;

[0031] Figure 2 is a scanning electron microscope image of the polydopamine modified fiber membrane of the present invention;

[0032] Figure 3 is a schematic structural diagram of a self-powered tactile sensor with a pressure-sensitive microstructure according to the present invention;

[0033] Figure 4 is a graph showing the resistance change rate (ΔR / R) of the self-powered tactile sensor of the present invention as a function of the applied pressure (P);

[0034] In the figure, 1-first flexible substrate, 2-pressure sensitive layer, 3-conducting wire, 4-second flexible substrate, 5-moisture power generation layer, 6-electrode, 7-breathable protective layer. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Embodiments of the present invention are as follows:

[0037] Embodiment 1:

[0038] like Figure 1 As shown, a polyimide (PI) film is used as the first flexible substrate 1, and a polydimethylsiloxane (PDMS) prepolymer doped with carbon nanotubes (CNT) is poured on the first flexible substrate 1 and cured at 80°C for 60 minutes to obtain a pressure sensitive layer 2. A wire 301 and a wire 302 are respectively led out at both ends of the pressure sensitive layer 2. Then, a PI film is attached to the upper surface of the pressure sensitive layer 2 as a second flexible substrate 4.

[0039] The polyaniline (PANI) nanofiber membrane was prepared by electrospinning, with a fiber diameter in the range of 200-5000nm and a membrane thickness of 5-10μm. The PANI fiber membrane was carbonized at high temperature in a muffle furnace to obtain a carbon nanofiber membrane. The carbon nanofiber membrane was immersed in a dopamine solution at an inclination angle of 30-90° and allowed to stand for 3h for oxidative polymerization reaction, and a polydopamine hydrophilic layer was deposited on the fiber surface to obtain a polydopamine modified fiber membrane with a polydopamine loading gradient and a water absorption capacity gradient, as a moisture generation layer, and its morphology is shown in Figure 5. Figure 2 As shown. Electrodes 601 and 602 are sputtered at both ends of the moisture power generation layer 5, and are led out by wires 303 and 304. The moisture power generation layer 5 is adhered to the second flexible substrate 4. A 300-mesh nylon mesh is covered on the moisture power generation layer 5 as a breathable protective layer 7, and a self-powered tactile sensor with moisture power generation function is obtained.

[0040] When the self-powered tactile sensor is working, firstly, a voltage and current meter and a load resistor are connected at both ends of the wire 303 and the wire 304, and a standard fitting curve is drawn according to the voltage and current values ​​measured when the external humidity and the load resistance change. A power supply is connected at both ends of the pressure-sensitive layer 2, and its IV curve is tested to establish the relationship between the resistance change rate and the pressure, and a resistance-pressure standard fitting curve is drawn; then, the two ends of the pressure-sensitive layer 2 are connected to the voltage meter and the current meter through the wire 301 and the wire 302, and the voltage on both sides of the pressure-sensitive layer 2 and the current in the circuit are detected to calculate the resistance, and the resistance is substituted into the resistance-pressure standard fitting curve to reversely infer the applied pressure. The sensing performance of the self-powered tactile sensor in different environments is tested. While detecting the pressure information, the pressure-sensitive layer 2 is used as the load, and the real-time environmental humidity is calculated by means of the relationship model between the output voltage at both ends of the moisture power generation layer 5 and the load resistance and humidity, so as to realize the synchronous detection of pressure and humidity.

[0041] Embodiment 2:

[0042] like Figure 3 As shown, polyester (PET) is used as the first flexible substrate 1. PDMS is poured into a template with a microstructure and cured at 80°C for 60 minutes to obtain a PDMS film with a microstructure; the surface of the PDMS film with a microstructure is treated with plasma, and then a graphene oxide (GO) suspension (1-5 mg / mL) is coated on the surface, and after drying at 50°C, the GO layer is simultaneously cross-linked and reduced using silane vapor to form a conductive coating of reduced graphene oxide (RGO), thereby obtaining a pressure-sensitive layer 2 with a microstructure. The pressure-sensitive layer 2 is attached to the first flexible substrate 1, and wires 301 and 302 are led out at both ends of the pressure-sensitive layer 2. A PET film is then attached to the upper surface of the pressure-sensitive layer 2 as the second flexible substrate 4.

[0043] Polyacrylonitrile (PAN) nanofiber membranes were prepared by electrospinning, with fiber diameters ranging from 200 to 5000 nm and membrane thicknesses of 5 to 10 μm. The PAN fiber membranes were carbonized at high temperature in a muffle furnace to obtain carbon nanofiber membranes. The carbon nanofiber membranes were immersed in a dopamine solution at an inclination angle of 30 to 90°, and allowed to stand for 3 hours for oxidative polymerization, and a polydopamine hydrophilic layer was deposited on the fiber surface to obtain a polydopamine modified fiber membrane having a polydopamine loading gradient and a water absorption capacity gradient, as a moisture power generation layer 5. Electrodes 601 and 602 were sputtered at both ends of the moisture power generation layer 5, and were led out using wires 303 and 304. The moisture power generation layer 5 was adhered to the second flexible substrate 4. A 300-mesh nylon mesh was covered on top of the moisture power generation layer 5 as a breathable protective layer 7 to obtain a self-powered tactile sensor with moisture power generation function.

[0044] When the self-powered tactile sensor is working, firstly, a voltage and current meter and a load resistor are connected at both ends of the wire 303 and the wire 304, and a standard fitting curve is drawn according to the voltage and current values ​​measured when the external humidity and the load resistance change. A power supply is connected at both ends of the pressure-sensitive layer 2, and its IV curve is tested to establish the relationship between the resistance change rate and the pressure, and a resistance-pressure standard fitting curve is drawn; then, the two ends of the pressure-sensitive layer 2 are connected to the voltage meter and the current meter through the wire 301 and the wire 302, and the voltage on both sides of the pressure-sensitive layer 2 and the current in the circuit are detected to calculate the resistance, and the applied pressure is inferred by substituting it into the resistance-pressure standard fitting curve.

[0045] The sensing performance of the self-powered tactile sensor in different environments was tested. While detecting pressure information, the pressure sensitive layer 2 was used as a load. The relationship model between the output voltage at both ends of the moisture power generation layer 5 and the load resistance and humidity was used to calculate the real-time environmental humidity, thereby realizing the simultaneous detection of pressure and humidity. Figure 4 As shown, the absolute value of the resistance change rate (ΔR / R) of the obtained tactile sensor increases continuously with the increase of the applied pressure (P), and shows a sensitivity (S1) of -6.81 / kPa in the low pressure area (<100kPa), and a sensitivity (S2) of -0.43 / kPa in the high pressure area (>100kPa).

Claims

1. A moisture-driven self-powered flexible tactile sensor, characterized in that: The invention mainly comprises a first flexible substrate (1), a pressure sensitive layer (2), a second flexible substrate (4), a moisture power generation layer (5) and a breathable protective layer (7) which are sequentially stacked from bottom to top; electrodes (6) are provided at both ends of the moisture power generation layer (5), and the electrodes (6) at both ends are led out through wires (303, 304); and both ends of the pressure sensitive layer (2) are led out through wires (301, 302); The moisture power generation layer (5) is made of a carbon nanofiber membrane modified with polydopamine and has a water absorption capacity gradient inside; The moisture power generation layer (5) is prepared by modifying dopamine in the following manner: Firstly, a polymer nanofiber membrane is prepared by an electrospinning method, and then the polymer nanofiber membrane is carbonized at a high temperature to obtain a carbon nanofiber membrane; The carbon nanofiber membrane is immersed in a dopamine solution, and a polydopamine hydrophilic layer is deposited on the fiber surface by an oxidative polymerization reaction, thereby obtaining a polydopamine-modified fiber membrane with a water absorption capacity gradient as a wet gas power generation material; When the self-powered flexible tactile sensor is working, firstly, a voltage and current meter and a load resistor are connected at both ends of the wires (303, 304), and a standard fitting curve is drawn according to the voltage and current values ​​measured when the external humidity and the load resistance change; a power supply is connected at both ends of the pressure sensitive layer (2), and its IV curve is tested to establish the relationship between the resistance change rate and the pressure, and a resistance-pressure standard fitting curve is drawn; then, the two ends of the pressure sensitive layer (2) are connected to the voltage meter and the current meter through the wires (301, 302), and the voltage at both ends of the pressure sensitive layer (2) and the current in the circuit are detected to calculate the resistance, and the resistance is substituted into the resistance-pressure standard fitting curve to reversely infer the applied pressure; the sensing performance of the self-powered flexible tactile sensor in different environments is tested, and while detecting the pressure information, the pressure sensitive layer (2) is used as a load, and the real-time environmental humidity is calculated by means of the relationship model between the output voltage at both ends of the moisture power generation layer (5) and the load resistance and humidity, so as to achieve synchronous detection of pressure and humidity.

2. The moisture-driven self-powered flexible tactile sensor according to claim 1, characterized in that: An electrode (6) is arranged at each end of the moisture power generation layer (5) along the gradient direction.

3. The moisture-driven self-powered flexible tactile sensor according to claim 1, characterized in that: The pressure sensitive layer (2) is made of a pressure sensitive film material.

4. The moisture-driven self-powered flexible tactile sensor according to claim 1, characterized in that: The breathable protective layer (7) is made of a porous breathable film material.

5. The moisture-driven self-powered flexible tactile sensor according to claim 1, characterized in that: A microstructure is arranged on the upper surface of the pressure sensitive layer (2).

6. The moisture-driven self-powered flexible tactile sensor according to claim 1, characterized in that: During the electrospinning preparation process, the process parameters are adjusted to control the diameter of the fibers in the polymer nanofiber membrane to be 200-5000nm, and the thickness of the polymer nanofiber membrane to be in the range of 5-10μm.

7. The method for preparing the self-powered flexible tactile sensor according to any one of claims 1 to 6, characterized in that: The preparation method comprises: S1, attaching a pressure sensitive layer (5) on a first flexible substrate (1), connecting two ends of the pressure sensitive layer (5) to wires, and adhering a second flexible substrate (4) above the pressure sensitive layer (5); S2. Modifying the polymer nanofiber membrane using dopamine to obtain wet gas power generation materials; S3, using micro-nano processing technology to prepare electrodes at both ends of the wet gas power generation material along the gradient direction, and connecting the electrodes at both ends to an external load to obtain a wet gas power generation layer (5), and adhering the wet gas power generation layer (5) to the second flexible substrate (4); S4. Covering the moisture power generation layer (5) with a layer of porous mesh film material as a breathable protective layer (7) to obtain a self-powered tactile sensor with moisture power generation function.

8. The method for preparing the self-powered flexible tactile sensor according to claim 7, characterized in that: The pressure sensitive layer (5) is a pressure sensitive layer with a microstructure on its upper surface.

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