Self-powered wireless humidity sensor as well as preparation method and use method thereof

Abstract

The invention discloses a self-powered wireless humidity sensor as well as a preparation method and a use method thereof. The preparation method comprises the following steps: A, preparing a carbon-based polymer film; b, laser processing is conducted on the carbon-based polymer film, a graphene electrode pattern is obtained, the graphene electrode pattern comprises a humidity sensing area, a point discharge area and an energy collection area, the humidity sensing area is used for sensing environment humidity and generating environment humidity signals, and the point discharge area is used for emitting the environment humidity signals; c, covering the energy collection area with a fluoropolymer film; wherein the fluoropolymer film and the energy harvesting area are jointly used for providing electric energy. According to the scheme, a circuit pattern is customized on the flexible substrate through laser, electric charges generated by triboelectrification and electrostatic induction are used for supplying energy to the sensor, meanwhile, wireless sensing of the sensor is achieved based on the point discharge principle, the sensor is used for wireless monitoring of the humidity in the environment, the sensor is simple and reasonable in structure, the preparation method is simple and rapid, and the cost is low. The use method is simple and accurate.

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 home, agricultural monitoring and industrial process control, the demand for humidity sensing technology is increasing. Traditional humidity sensors usually rely on external power or built-in batteries, which leads to problems such as frequent equipment maintenance, high cost and poor convenience. Therefore, it is of great significance to develop a self-powered wireless humidity sensing system.

[0003] At present, commercial humidity sensors generally face the problem of structural complexity. Most humidity sensors rely on multiple independent components, including signal sensing modules, signal processing modules, power modules and signal transmission modules. Such a separate design not only increases the size and weight of the equipment, making installation and maintenance in certain application scenarios more cumbersome, but also the connection between the modules requires a rigid substrate, further limiting the flexibility and adaptability of the system. In addition, traditional humidity sensors also face considerable challenges in terms of energy consumption. Many devices need to rely on external power supplies or frequent battery replacement, which increases the cost of use and maintenance burden.

[0004] Laser-induced graphene technology provides new possibilities for the design and processing of humidity sensors. This technology is not only easy and fast to process, but also can effectively integrate various functional modules into a single humidity sensor module. This integrated design not only improves the stability and sensitivity of the device, but also significantly reduces the complexity and cost of the manufacturing process. The integration solution based on laser-induced graphene technology not only realizes modular design, but also can continuously and reliably monitor environmental humidity through self-powered mode, which greatly improves the universality and market competitiveness of the equipment.

[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 a preparation method and a use method thereof. The circuit pattern is customized on a flexible substrate by laser, and the charges generated by friction electrification and electrostatic induction are used to power the sensor. At the same time, the 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 has a simple and reasonable structure, a simple and quick preparation method, and a simple and accurate use method, which can effectively overcome the shortcomings of the prior art.

[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 films;

[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 comprises a humidity sensing region, a tip discharge region and an energy collection region which 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 an 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 carbon-based polymer film has a thickness of 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 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 manufacturing 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, comprising 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 an 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 a test environment, 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 to 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 tested based on the mapping relationship between the frequency and the 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 analyzing 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 may include 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 a method for preparing a self-powered wireless humidity sensor of the present invention.

[0031] Figure 3 It is a schematic diagram of the graphene electrode pattern in the present invention.

[0032] Figure 4 It is a schematic diagram of step C in a 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 region 201, tip discharge region 202, energy collection region 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] The present 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 which 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 an 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-powering 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 friction electrification 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 graphene electrodes. In a preferred embodiment, the present solution may also place the carbon-based polymer film 1 on a laser-assisted substrate 7, such as Figure 1As shown, it is helpful to keep the carbon-based polymer film 1 in a horizontal plane, and 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 is helpful to improve the consistency of the quality of the graphene produced by the processing. It should be noted that the laser-assisted substrate 7 of this solution can be an acrylic plate or a glass sheet.

[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 above three parts are connected by graphene processed by laser, which respectively play the role of signal sensing, signal transmission and energy collection. Among them, the realization principle of the humidity sensing area 201 is: when the humidity of the environment to be measured changes, the air medium between the graphene electrodes of the humidity sensing area 201 changes with the change of humidity, and its dielectric constant will also change, so the capacitance value of the humidity sensing area 201 will also change accordingly, and different capacitance values ​​correspond to different humidity, thereby achieving the purpose of humidity sensing.

[0048] It should be noted that the graphene electrode pattern 2 of the present solution can be processed in one step by a picosecond laser device. Compared with the traditional wireless sensor device which requires a power module, a signal sensing module, a signal processing module and a signal transmitting module, which are all different electronic component units and are connected to a rigid circuit board, the present technical solution uses a laser one-step method for processing on a flexible substrate, which 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 negative electrode material (i.e., fluoropolymer film 3 with very strong electron-acquiring ability) to the energy collection region 203 so as to realize the supply of electrons, such as Figure 4 As shown. It should be noted that the realization principle of the tip discharge area 202 and the energy collection area 203 is as follows: the graphene electrode located in the energy collection area 203 acts as a conductor, and the fluoropolymer film 3 covering the surface of the area 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 friction electrification and electrostatic induction, a potential difference will be generated at both ends of the graphene electrode in the energy collection area 203, thereby realizing self-power supply; and the above-mentioned potential difference can cause the tip (i.e., the tip discharge area 202) of the entire loop (i.e., the graphene electrode pattern 2) to generate discharge, and the discharge will generate a high-frequency signal, thereby realizing the 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 electrode of the humidity sensing area 201 is an interdigitated electrode, which is more conducive to accurately capturing the 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 can achieve a high absorption rate within the above-mentioned laser wavelength range. A wavelength that is too long or too short may affect the absorption of the laser by the carbon-based polymer film 1, thereby affecting the processing efficiency and energy utilization. In addition, the laser power is preferably set to 1 to 5 W, which is conducive to ensuring the processing quality of the graphene electrode and avoiding the shedding of the graphene 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 the present embodiment is preferably 30-100 μm. If the film is too thin, it is easy to be 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 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 decrease, limiting its effectiveness in flexible applications.

[0059] A self-powered wireless humidity sensor is manufactured by the manufacturing 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 multiple modules and rigid substrates (such as PCB boards, ceramic substrates, etc.) 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, comprising 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 making the distance between the self-powered wireless humidity sensor and the metal coil 4 be at most 2 meters;

[0064] (3) Using a finger to 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 above 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 needs to 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, by reading the detection frequency of the host computer, the humidity in the current detection environment is obtained according to the above-mentioned pre-formed mapping relationship. This is because different processing methods, materials, parameters of each graphene shape, and parameters of the coil will affect the mapping relationship between frequency and corresponding humidity, so it is necessary to perform pre-calibration.

[0068] To further explain, 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 the present technical solution, the number of turns of the metal coil 4 is 5 to 20. The more turns, the higher the inductance value. Too few turns may not be able to obtain sufficient inductance value, thus affecting signal reception; too many turns may cause the coil volume and inductance to be too large, thus causing signal attenuation.

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

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

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

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

[0074] When the present solution uses an oscilloscope as the signal testing and analyzing 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 the host computer 6 is interconnected with the oscilloscope using LabVIEW software.

[0078] (2) placing the self-powered wireless humidity sensor in the test environment, and setting 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 mm 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 which are interconnected;

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

[0083] (3) Use a finger to swipe from the first block electrode of the energy collection region 203 to the second block electrode;

[0084] (4) The current frequency is read from the host computer 6 as 8.38 MHz, and the humidity of the environment to be tested is obtained as 70% according to the mapping relationship between the frequency and the 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 the host computer 6 is interconnected with the oscilloscope using LabVIEW software.

[0087] (2) placing the self-powered wireless humidity sensor in the test environment, and setting 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 mm 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 which are interconnected;

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

[0092] (3) Use a finger to swipe from the first block electrode of the energy collection area 203 to the second block electrode;

[0093] (4) The current frequency is read from the host computer 6 as 4.75 MHz, and the humidity of the environment to be tested is obtained as 80% according to the mapping relationship between the frequency and the 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 the host computer 6 is interconnected with the oscilloscope using LabVIEW software.

[0096] (2) placing the self-powered wireless humidity sensor in the test environment, and setting 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 mm 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 which are interconnected;

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

[0101] (3) Use a finger to swipe from the first block electrode of the energy collection region 203 to the second block electrode;

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

[0103] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods 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 films; B. performing laser processing on the surface of the carbon-based polymer film to obtain a graphene electrode pattern; wherein the graphene electrode pattern comprises a humidity sensing region, a tip discharge region and an energy collection region which 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 an ambient humidity signal; 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, characterized in that: 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.

3. The method for preparing a self-powered wireless humidity sensor according to claim 2, characterized in that: 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, characterized in that: 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, characterized in that: In step C, the thickness of the fluoropolymer film is 20-80 μm, and the fluoropolymer film includes 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 an 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 a test environment, 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 to 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 tested based on the mapping relationship between the frequency and the 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, characterized in that: The signal testing and analyzing device 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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