A self-powered wireless humidity sensor and its preparation method and use method

Abstract

The present invention discloses a self-powered wireless humidity sensor and its preparation and use methods. The preparation method comprises: A. preparing a carbon-based polymer film; B. laser processing the carbon-based polymer film to obtain a graphene electrode pattern, wherein the graphene electrode pattern includes a humidity sensing region, a tip discharge region, and an energy collection region. The humidity sensing region is used to sense ambient humidity and generate an ambient humidity signal, and the tip discharge region is used to transmit the ambient humidity signal; C. covering the energy collection region with a fluoropolymer film; wherein the fluoropolymer film and the energy collection region are used together to provide electrical energy. This solution uses a laser to customize a circuit pattern on a flexible substrate, utilizes charges generated by triboelectric charging and electrostatic induction to power the sensor, and simultaneously implements wireless sensing based on the tip discharge principle for wireless monitoring of humidity in the environment. The sensor has a simple and reasonable structure, a simple and quick preparation method, and a simple and accurate use method.

Description

Technical Field

[0001] The present invention relates to the technical field of self-powered wireless sensors, and in particular to a self-powered wireless humidity sensor and a preparation method and a use method thereof. Background Art

[0002] With the continuous development of smart homes, agricultural monitoring, and industrial process control, the demand for humidity sensing technology is increasing. Traditional humidity sensors typically rely on external power supplies or internal batteries, which leads to frequent maintenance, high costs, and poor usability. Therefore, the development of a self-powered wireless humidity sensing system is of great significance.

[0003] Currently, commercial humidity sensors generally face the problem of structural complexity. Most humidity sensors rely on multiple independent components, including a signal sensing module, a signal processing module, a power module, and a signal transmission module. This separate design not only increases the size and weight of the device, making installation and maintenance more cumbersome in certain application scenarios, but also requires a rigid substrate for connections between the modules, further limiting the flexibility and adaptability of the system. Furthermore, traditional humidity sensors also present significant challenges in terms of energy consumption. Many devices require external power supplies or frequent battery replacement, which increases usage costs and maintenance burdens.

[0004] Laser-induced graphene technology offers new possibilities for the design and fabrication of humidity sensors. This technology not only allows for simple and rapid fabrication but also effectively integrates various functional modules into a single humidity sensor module. This integrated design not only improves device stability and sensitivity but also significantly reduces manufacturing complexity and costs. This integrated solution based on laser-induced graphene technology not only enables modular design but also allows for continuous and reliable monitoring of ambient humidity through self-powered operation, significantly enhancing the device's universality and market competitiveness.

[0005] Therefore, there is an urgent need to provide a self-powered wireless humidity sensor to address the shortcomings of existing humidity sensor devices. Summary of the Invention

[0006] The purpose of the present invention is to propose a self-powered wireless humidity sensor and its preparation method and use method. The circuit pattern is customized on a flexible substrate by laser, and the charge generated by friction electrification and electrostatic induction is used to power the sensor. At the same time, wireless sensing of the sensor is realized based on the tip discharge principle, so as to be used for wireless monitoring of humidity in the environment. The sensor structure is simple and reasonable, the preparation method is simple and fast, and the use method is simple and accurate, which can effectively overcome the shortcomings of the existing technology.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A method for preparing a self-powered wireless humidity sensor comprises the following steps:

[0009] A. Prepare carbon-based polymer film;

[0010] B. performing laser processing on the surface of the carbon-based polymer film to obtain a graphene electrode pattern; wherein the graphene electrode pattern includes a humidity sensing region, a tip discharge region, and an energy collection region that are interconnected, and the humidity sensing region is used to sense ambient humidity and generate an ambient humidity signal, and the tip discharge region is used to transmit the ambient humidity signal;

[0011] C. Covering the surface of the energy collection area with a fluoropolymer film to obtain a self-powered wireless humidity sensor; wherein the fluoropolymer film and the energy collection area are used together to provide electrical energy for the self-powered wireless humidity sensor.

[0012] Preferably, the humidity sensing region is an interdigitated electrode, the tip discharge region includes a first tip electrode and a second tip electrode separated from each other, and the energy collection region includes a first block electrode and a second block electrode separated from each other.

[0013] Preferably, in step B, the wavelength of the laser is 300-400 nm, and the laser power is 1-5 W.

[0014] Preferably, in step A, the thickness of the carbon-based polymer film is 30-100 μm, and the carbon-based polymer film includes any one of a polyimide film, a polyetherimide film and a polyester film.

[0015] Preferably, in step C, the thickness of the fluoropolymer film is 20-80 μm, and the fluoropolymer film includes any one of a fluorinated ethylene propylene copolymer film, a polytetrafluoroethylene film and a polyvinylidene fluoride film.

[0016] A self-powered wireless humidity sensor is manufactured by the above-mentioned preparation method of the self-powered wireless humidity sensor.

[0017] A method for using a self-powered wireless humidity sensor, using the self-powered wireless humidity sensor, includes the following steps:

[0018] (1) electrically connecting a metal coil, a signal testing and analysis device, and a host computer in sequence; wherein the metal coil is used to receive the ambient humidity signal emitted by the tip discharge area, the signal testing and analysis device is used to read the ambient humidity signal, and the host computer is used to analyze and process the ambient humidity signal;

[0019] (2) placing the self-powered wireless humidity sensor in the environment to be tested, and ensuring that the distance between the self-powered wireless humidity sensor and the metal coil is at most 2 meters;

[0020] (3) Using a finger, swipe from the first block electrode to the second block electrode in the energy collection area;

[0021] (4) Read the current frequency from the host computer and obtain the humidity of the environment to be measured based on the mapping relationship between frequency and ambient humidity.

[0022] Preferably, the number of turns of the metal coil is 5 to 20, and the wire diameter of the metal coil is 20 to 100 μm.

[0023] Preferably, the signal testing and analysis equipment is any one of an oscilloscope and a spectrum analyzer.

[0024] Preferably, the sampling frequency of the oscilloscope is 125-250 Mbps.

[0025] The technical solution provided by the present invention can have the following beneficial effects:

[0026] 1. The self-powered wireless humidity sensor provided by the present invention does not require external energy and can achieve self-powered wireless sensing.

[0027] 2. The self-powered wireless humidity sensor provided by the present invention is made by one-step laser processing, which is simple and fast and suitable for large-scale production.

[0028] 3. The self-powered wireless humidity sensor provided by the present invention abandons the multiple modules and rigid substrates in the traditional sensing system, making the entire system flexible and more integrated, and the volume of the sensing system can be customized according to the application scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of step A in a method for preparing a self-powered wireless humidity sensor of the present invention.

[0030] Figure 2 It is a schematic diagram of step B in the method for preparing a self-powered wireless humidity sensor of the present invention.

[0031] Figure 3 Schematic diagram of the graphene electrode pattern in the present invention.

[0032] Figure 4 It is a schematic diagram of step C in the method for preparing a self-powered wireless humidity sensor of the present invention.

[0033] Figure 5 The present invention is a flowchart of a method for using a self-powered wireless humidity sensor.

[0034] in:

[0035] Carbon-based polymer film 1;

[0036] Graphene electrode pattern 2, humidity sensing area 201, tip discharge area 202, energy collection area 203;

[0037] Fluoropolymer film 3;

[0038] Metal coil 4, signal testing and analysis equipment 5, host computer 6;

[0039] Laser assisted substrate 7. DETAILED DESCRIPTION

[0040] This technical solution provides a method for preparing a self-powered wireless humidity sensor, comprising the following steps:

[0041] A. Prepare a carbon-based polymer film 1;

[0042] B. Laser processing is performed on the surface of the carbon-based polymer film 1 to obtain a graphene electrode pattern 2; wherein the graphene electrode pattern 2 includes a humidity sensing region 201, a tip discharge region 202, and an energy collection region 203 that are interconnected, and the humidity sensing region 201 is used to sense ambient humidity and generate an ambient humidity signal, and the tip discharge region 202 is used to transmit the ambient humidity signal;

[0043] C. Covering the surface of the energy collection area 203 with a fluoropolymer film 3 to obtain a self-powered wireless humidity sensor; wherein the fluoropolymer film 3 and the energy collection area 203 are used together to provide electrical energy for the self-powered wireless humidity sensor.

[0044] In order to achieve self-powered and wireless transmission of the humidity sensor, this technical solution proposes a method for preparing a self-powered wireless humidity sensor. The circuit pattern is customized on a flexible substrate by laser, and the charge generated by triboelectric charging and electrostatic induction is used to power the sensor. At the same time, the wireless sensing of the sensor is realized based on the tip discharge principle, thereby realizing wireless monitoring of the humidity in the environment.

[0045] Specifically, the preparation method of this scheme includes the following steps:

[0046] Step A: Prepare a carbon-based polymer film 1, i.e., a processing substrate for the graphene electrode. In a preferred embodiment, the present invention can also place the carbon-based polymer film 1 on a laser-assisted substrate 7, such as Figure 1As shown, this helps keep the carbon-based polymer film 1 in a horizontal plane. When the laser processing is performed in step B, the distance between the processing equipment and the carbon-based polymer film 1 remains consistent, which helps improve the consistency of the quality of the graphene produced by the processing. It should be noted that the laser-assisted substrate 7 in this solution can be an acrylic plate or a glass sheet, etc.

[0047] Step B is the core of this solution. The graphene electrode pattern 2 processed by laser in one step has three parts: humidity sensing area 201, tip discharge area 202 and energy collection area 203. Figure 2-3 As shown, the three components are connected by laser-processed graphene, serving as signal sensing, signal transmission, and energy collection, respectively. The humidity sensing region 201 operates on the principle that when the humidity of the measured environment changes, the dielectric constant of the air medium between the graphene electrodes in the humidity sensing region 201 also changes with the humidity. Consequently, the capacitance value of the humidity sensing region 201 also changes accordingly. Different capacitance values correspond to different humidity levels, thus achieving the purpose of humidity sensing.

[0048] It should be noted that the graphene electrode pattern 2 of this solution can be processed in one step by a picosecond laser device. Compared with traditional wireless sensing devices that require a power module, a signal sensing module, a signal processing module, and a signal transmission module, which are all different electronic component units and are connected to a rigid circuit board, this technical solution uses a one-step laser method for processing on a flexible substrate. It has the characteristics of simple and fast process and is suitable for large-scale production. The entire sensor is flexible and more integrated, and the volume of the sensor can be customized according to the application scenario, thereby improving the applicability of the sensor.

[0049] Step C is to provide the energy collection region 203 with a negative electrode material (i.e., a fluoropolymer film 3 with a very strong electron-acquisition capability) so as to facilitate the supply of electrons, such as Figure 4 As shown. It should be noted that the implementation principle of the tip discharge region 202 and the energy collection region 203 is as follows: the graphene electrode located in the energy collection region 203 acts as a conductor, and the fluoropolymer film 3 covering the surface of the region acts as a negative electrode material to provide an electron source. When a finger or other object passes over the fluoropolymer film 3, due to the principles of triboelectric charging and electrostatic induction, a potential difference is generated across the graphene electrode in the energy collection region 203, achieving self-energy supply. This potential difference can also cause the tip (i.e., the tip discharge region 202) of the entire loop (i.e., the graphene electrode pattern 2) to generate a discharge, which generates a high-frequency signal, thereby achieving wireless transmission of the ambient humidity signal.

[0050] To further illustrate, the humidity sensing region 201 is an interdigitated electrode, the tip discharge region 202 includes a first tip electrode and a second tip electrode separated from each other, and the energy collection region 203 includes a first block electrode and a second block electrode separated from each other.

[0051] In a preferred embodiment of the present technical solution, the graphene electrodes in the humidity sensing area 201 are interdigitated electrodes, which are more conducive to accurately capturing humidity changes in the environment to be measured and improving the accuracy of the self-powered wireless humidity sensor.

[0052] It should be noted that the shape of the block electrodes in the energy collection area 203 in this solution can be a rectangle, a parallelogram or a triangle, which is not limited here.

[0053] To further illustrate, in step B, the wavelength of the laser is 300-400 nm, and the laser power is 1-5 W.

[0054] The carbon-based polymer film 1 used in this solution achieves a high absorption rate within the aforementioned laser wavelength range. Excessively long or short wavelengths may affect the carbon-based polymer film 1's absorption of the laser, thereby affecting processing efficiency and energy utilization. Furthermore, a laser power of 1 to 5 W is preferred to ensure the processing quality of the graphene electrode and prevent graphene shedding after processing.

[0055] To further illustrate, in step A, the thickness of the carbon-based polymer film 1 is 30-100 μm, and the carbon-based polymer film 1 includes any one of a polyimide film, a polyetherimide film, and a polyester film.

[0056] Furthermore, the thickness of the carbon-based polymer film 1 of this embodiment is preferably 30-100 μm. If the film is too thin, it is easily directly ablated by the laser, affecting the integrity of the device. If the film is too thick, it affects the flexibility of the entire device.

[0057] To further illustrate, in step C, the thickness of the fluoropolymer film 3 is 20-80 μm, and the fluoropolymer film 3 includes any one of a fluorinated ethylene propylene copolymer film, a polytetrafluoroethylene film, and a polyvinylidene fluoride film.

[0058] Furthermore, the thickness of the fluoropolymer film 3 of the present embodiment is preferably 20 to 80 μm. If the film is too thin, the device may be easily torn or damaged during use, reducing durability. If the film is too thick, the flexibility of the device may be reduced, limiting its effectiveness in flexible applications.

[0059] A self-powered wireless humidity sensor is manufactured by the above-mentioned preparation method of the self-powered wireless humidity sensor.

[0060] The self-powered wireless humidity sensor provided in this solution does not require external energy and can achieve self-powered wireless sensing. The device abandons the multiple modules and rigid substrates (such as PCB boards and ceramic substrates) in traditional sensing systems, making the entire sensing system flexible and more integrated. The volume of the sensing system can be customized according to the application scenario, making it more applicable.

[0061] A method for using a self-powered wireless humidity sensor, using the self-powered wireless humidity sensor, includes the following steps:

[0062] (1) The metal coil 4, the signal testing and analysis device 5, and the host computer 6 are electrically connected in sequence; wherein the metal coil 4 is used to receive the ambient humidity signal emitted by the tip discharge area 202, the signal testing and analysis device 5 is used to read the ambient humidity signal, and the host computer 6 is used to analyze and process the ambient humidity signal;

[0063] (2) placing the self-powered wireless humidity sensor in the environment to be tested, and ensuring that the distance between the self-powered wireless humidity sensor and the metal coil 4 is at most 2 meters;

[0064] (3) Using a finger, swipe from the first block electrode to the second block electrode in the energy collection area 203;

[0065] (4) Read the current frequency from the host computer 6 and obtain the humidity of the environment to be measured based on the mapping relationship between the frequency and the ambient humidity.

[0066] This technical solution also proposes a method for using the self-powered wireless humidity sensor, which can achieve an effective wireless transmission distance of less than 2 meters. The flow chart is as follows: Figure 5 shown.

[0067] It should be noted that in step (4) of the method of use, the humidity sensor must first be placed in an environment with a specific humidity to obtain a mapping relationship between frequency and corresponding humidity (such as a formula algorithm or a fitting curve). In the subsequent environmental humidity detection process, the humidity in the current detection environment is obtained by reading the detection frequency of the host computer based on the above pre-formed mapping relationship. This is because different processing methods, materials, parameters of various graphene shapes, and parameters of the coil will affect the mapping relationship between frequency and corresponding humidity, so pre-calibration is required.

[0068] To further illustrate, the number of turns of the metal coil 4 is 5 to 20, and the wire diameter of the metal coil 4 is 20 to 100 μm.

[0069] In this technical solution, the number of turns of the metal coil 4 is 5 to 20. The more turns, the higher the inductance. Too few turns may not achieve sufficient inductance, thus affecting signal reception; too many turns may lead to excessive coil volume and inductance, resulting in signal attenuation.

[0070] In addition, the wire diameter of the metal coil 4 in this technical solution is 20-100 μm. Too thin a wire diameter may increase the resistance of the coil and reduce signal quality; while a thicker wire diameter will increase the overall volume of the coil and increase the turn spacing, affecting the concentration of magnetic flux.

[0071] Preferably, the metal coil 4 of this solution can be a copper coil, a transformer coil or a winding coil, which is not limited here.

[0072] To further illustrate, the signal testing and analysis device 5 is any one of an oscilloscope and a spectrum analyzer.

[0073] To further illustrate, the sampling frequency of the oscilloscope is 125-250 Mbps.

[0074] When the present solution uses an oscilloscope as the signal testing and analysis device 5 , its sampling frequency is also optimized to facilitate identification of high-frequency signals generated by tip discharge and avoid loss of signal features, thereby improving detection accuracy.

[0075] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0076] Example 1

[0077] (1) A copper coil with 10 turns and a wire diameter of 0.05 mm, an oscilloscope with a sampling frequency of 125 to 250 Mbps, and a host computer 6 are electrically connected in sequence, and LabVIEW software is used on the host computer 6 to interconnect with the oscilloscope.

[0078] (2) Place the self-powered wireless humidity sensor in the test environment, and set the distance between the self-powered wireless humidity sensor and the metal coil 4 to 0.6 meters;

[0079] The preparation method of the self-powered wireless humidity sensor is as follows:

[0080] A. Prepare a polyimide film with a thickness of 50 μm;

[0081] B. Laser processing is performed on the surface of the polyimide film using a picosecond ultraviolet laser with a wavelength of 355 nm and a power of 2.1 W to obtain a graphene electrode pattern 2; wherein the graphene electrode pattern 2 includes a humidity sensing region 201, a tip discharge region 202, and an energy collection region 203 that are interconnected;

[0082] C. Cover the surface of the energy collection area 203 with a fluorinated ethylene propylene copolymer film with a thickness of 30 μm to obtain a self-powered wireless humidity sensor.

[0083] (3) Use your finger to slide from the first block electrode to the second block electrode in the energy collection area 203;

[0084] (4) The current frequency read from the host computer 6 is 8.38 MHz, and the humidity of the environment to be tested is obtained as 70% based on the mapping relationship between frequency and ambient humidity.

[0085] Example 2

[0086] (1) A copper coil with 10 turns and a wire diameter of 0.05 mm, an oscilloscope with a sampling frequency of 125 to 250 Mbps, and a host computer 6 are electrically connected in sequence, and LabVIEW software is used on the host computer 6 to interconnect with the oscilloscope.

[0087] (2) Place the self-powered wireless humidity sensor in the test environment, and set the distance between the self-powered wireless humidity sensor and the metal coil 4 to 0.6 meters;

[0088] The preparation method of the self-powered wireless humidity sensor is as follows:

[0089] A. Prepare a polyimide film with a thickness of 50 μm;

[0090] B. Laser processing is performed on the surface of the polyimide film using a picosecond ultraviolet laser with a wavelength of 355 nm and a power of 2.1 W to obtain a graphene electrode pattern 2; wherein the graphene electrode pattern 2 includes a humidity sensing region 201, a tip discharge region 202, and an energy collection region 203 that are interconnected;

[0091] C. Cover the surface of the energy collection area 203 with a fluorinated ethylene propylene copolymer film with a thickness of 30 μm to obtain a self-powered wireless humidity sensor.

[0092] (3) Use your finger to slide from the first block electrode to the second block electrode in the energy collection area 203;

[0093] (4) The current frequency read from the host computer 6 is 4.75 MHz, and the humidity of the environment to be tested is obtained as 80% based on the mapping relationship between frequency and ambient humidity.

[0094] Example 3

[0095] (1) A copper coil with 10 turns and a wire diameter of 0.05 mm, an oscilloscope with a sampling frequency of 125 to 250 Mbps, and a host computer 6 are electrically connected in sequence, and LabVIEW software is used on the host computer 6 to interconnect with the oscilloscope.

[0096] (2) Place the self-powered wireless humidity sensor in the test environment, and set the distance between the self-powered wireless humidity sensor and the metal coil 4 to 0.6 meters;

[0097] The preparation method of the self-powered wireless humidity sensor is as follows:

[0098] A. Prepare a polyimide film with a thickness of 50 μm;

[0099] B. Laser processing is performed on the surface of the polyimide film using a picosecond ultraviolet laser with a wavelength of 355 nm and a power of 2.1 W to obtain a graphene electrode pattern 2; wherein the graphene electrode pattern 2 includes a humidity sensing region 201, a tip discharge region 202, and an energy collection region 203 that are interconnected;

[0100] C. Cover the surface of the energy collection area 203 with a fluorinated ethylene propylene copolymer film with a thickness of 30 μm to obtain a self-powered wireless humidity sensor.

[0101] (3) Use your finger to slide from the first block electrode to the second block electrode in the energy collection area 203;

[0102] (4) The current frequency read from the host computer 6 is 3.25 MHz, and the humidity of the environment to be tested is obtained as 90% based on the mapping relationship between frequency and ambient humidity.

[0103] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a self-powered wireless humidity sensor, characterized in that: The following steps are involved: A. Prepare carbon-based polymer film; B. performing laser processing on the surface of the carbon-based polymer film to obtain a graphene electrode pattern; wherein the graphene electrode pattern is composed of a humidity sensing region, a tip discharge region, and an energy collection region that are interconnected, wherein the humidity sensing region is used to sense ambient humidity and generate an ambient humidity signal, the tip discharge region is used to transmit the ambient humidity signal, and the energy collection region includes a first block electrode and a second block electrode that are separated from each other; C. Covering the surface of the energy collection area with a fluoropolymer film to obtain a self-powered wireless humidity sensor; wherein the fluoropolymer film and the energy collection area are used together to provide electrical energy for the self-powered wireless humidity sensor.

2. The method for preparing a self-powered wireless humidity sensor according to claim 1, wherein: The humidity sensing region is an interdigitated electrode, and the tip discharge region includes a first tip electrode and a second tip electrode that are separated from each other.

3. The method for preparing a self-powered wireless humidity sensor according to claim 2, wherein: In step B, the wavelength of the laser is 300-400 nm, and the laser power is 1-5 W.

4. The method for preparing a self-powered wireless humidity sensor according to claim 2, wherein: In step A, the thickness of the carbon-based polymer film is 30-100 μm, and the carbon-based polymer film includes any one of a polyimide film, a polyetherimide film and a polyester film.

5. The method for preparing a self-powered wireless humidity sensor according to claim 2, wherein: In step C, the thickness of the fluoropolymer film is 20 to 80 μm, and the fluoropolymer film includes any one of a fluorinated ethylene propylene copolymer film, a polytetrafluoroethylene film, and a polyvinylidene fluoride film.

6. A self-powered wireless humidity sensor, characterized in that: The self-powered wireless humidity sensor is prepared by the preparation method of any one of claims 2 to 5.

7. A method for using a self-powered wireless humidity sensor, characterized in that: Using the self-powered wireless humidity sensor according to claim 6 comprises the following steps: (1) electrically connecting a metal coil, a signal testing and analysis device, and a host computer in sequence; wherein the metal coil is used to receive the ambient humidity signal emitted by the tip discharge area, the signal testing and analysis device is used to read the ambient humidity signal, and the host computer is used to analyze and process the ambient humidity signal; (2) placing the self-powered wireless humidity sensor in the environment to be tested, and ensuring that the distance between the self-powered wireless humidity sensor and the metal coil is at most 2 meters; (3) Using a finger, swipe from the first block electrode to the second block electrode in the energy collection area; (4) Read the current frequency from the host computer and obtain the humidity of the environment to be measured based on the mapping relationship between frequency and ambient humidity.

8. The method for using a self-powered wireless humidity sensor according to claim 7, characterized in that: The number of turns of the metal coil is 5 to 20, and the wire diameter of the metal coil is 20 to 100 μm.

9. The method for using a self-powered wireless humidity sensor according to claim 7, wherein: The signal testing and analysis equipment is any one of an oscilloscope and a spectrum analyzer.

10. The method for using a self-powered wireless humidity sensor according to claim 9, characterized in that: The sampling frequency of the oscilloscope is 125-250 Mbps.

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