Low-power-consumption detection methane sensor and detection method thereof

Abstract

The invention discloses a low-power-consumption detection methane sensor and a detection method thereof, and belongs to the technical field of methane detection. The invention aims to realize room-temperature low-power-consumption detection of methane gas. An Au interdigital electrode is prepared on the upper surface of a polyimide film substrate through a chemical deposition method, a sensing area of the Au interdigital electrode is uniformly coated with a Pd-doped NH2-C3N4 / CoAl-LDHs nano sensing material layer, and the leading-out end of the Au interdigital electrode is connected with a horizontal pasting pin header; the double-row female header, the resistance acquisition chip, the Bluetooth module and the battery are sequentially mounted on a bottom plate of the rectangular cavity of the copper-clad laminate from left to right, one end of the double-row female header is connected with the resistance acquisition chip, and the resistance acquisition chip is connected with the Bluetooth module; the ultraviolet lamp is mounted on a top plate of the rectangular cavity of the copper-clad laminate; the horizontally-pasted pin header is connected with the other end of the double-row female header, and the battery is used for overall power supply of the methane sensor with the low-power-consumption detection function. The low-power-consumption detection of methane is realized.

Description

Technical Field

[0001] This invention belongs to the field of methane detection technology, specifically relating to a low-power methane sensor and its detection method. Background Technology

[0002] Methane, a flammable and explosive colorless and odorless gas, is widely present in industrial production and transportation, as well as in residential gas supply. Its leakage can easily lead to explosions, poisoning, and other safety accidents, making rapid and accurate detection of methane gas crucial. Currently, traditional methane sensors are mostly based on principles such as catalytic combustion and infrared absorption. These sensors often require high operating temperatures, resulting in high power consumption and the safety hazard of igniting the gas in high-concentration methane environments, making them unsuitable for low-power, safe detection scenarios. Meanwhile, existing room-temperature methane sensors generally suffer from low sensitivity, poor selectivity, and slow response recovery, failing to meet the stringent performance requirements of industrial leak early warning and residential gas monitoring. Therefore, developing a high-performance, low-power methane sensor has become an urgent technical challenge for the industry. Summary of the Invention

[0003] The problem to be solved by this invention is to achieve low-power detection of methane gas at room temperature, and to propose a low-power methane sensor and its detection method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A low-power methane sensor includes a polyimide thin film substrate, Au interdigitated electrodes, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer, horizontal pin headers, a rectangular cavity of a copper-clad laminate, a double-row header, a battery, an ultraviolet lamp, a resistance acquisition chip, and a Bluetooth module. The first device consists of a polyimide film substrate, Au interdigitated electrodes, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer, and horizontally mounted pins. Au interdigitated electrodes are prepared on the surface of the polyimide film substrate by chemical deposition. A Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer is uniformly coated on the sensing area of ​​the Au interdigitated electrodes. The leads of the Au interdigitated electrodes are connected to horizontally mounted pins. In the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3), Pd is doped in elemental form in the NH2-C3N4 / CoAl-LDHs composite material at a ratio of 1~3 wt%. The second device comprises a rectangular cavity of a copper-clad laminate, a double-row header, a battery, an ultraviolet lamp, a resistance acquisition chip, and a Bluetooth module. The double-row header, resistance acquisition chip, Bluetooth module, and battery are sequentially mounted from left to right on the bottom plate of the rectangular cavity of the copper-clad laminate. One end of the double-row header is connected to the resistance acquisition chip, which is connected to the Bluetooth module. The ultraviolet lamp is mounted on the top plate of the rectangular cavity of the copper-clad laminate. A first device is placed below the ultraviolet lamp, with its horizontal pin header connected to the other end of the double-row header. The battery provides overall power to a low-power methane sensor.

[0005] Furthermore, based on the area of ​​the sensing region being 5mm×10mm~10mm×20mm, the coating mass of the nanosensing material in the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer is set to be 0.5mg~50mg.

[0006] Furthermore, the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material has a nanoscale three-dimensional layered structure with a specific surface area of ​​10 m². 2 / g~50m 2 / g.

[0007] Furthermore, the preparation method of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 1 degree Celsius / minute, and calcine at a constant temperature of 500°C for 4 hours in an air atmosphere; after the muffle furnace cools naturally to room temperature, take out the calcined product, grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4 for later use; Step 2. Amine-modified carbon nitride (NH4N) 2- Preparation of C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker, stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the above mixed solvent, sonicate until the powder is completely dispersed; transfer the dispersion to a three-necked flask, place it in a 90℃ constant temperature oil bath, and react at a constant temperature for 12 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven, dry it at 60℃ for 24 hours, grind it after drying, and collect the NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.2333 g of cobalt nitrate hexahydrate, 0.15 g of aluminum nitrate nonahydrate, 0.15 g of ammonium fluoride, and 1.7 g of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in a forced-air drying oven. Heat at a constant temperature of 90℃~120℃ for 6 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60℃ for 24 hours. Collect the CoAl-LDHs powder for later use. Step 4. Preparation of NH2-C3N4 / CoAl-LDHs composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder and 1 g of CoAl-LDHs powder in sequence, and then add 0.03 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 2 hours to ensure that the two materials are fully composited; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min; collect the solid product after centrifugation, put it in a vacuum oven, dry at 60℃ for 24 hours, grind it to obtain the NH2-C3N4 / CoAl-LDHs composite material for later use; Step 5. Preparation of Pd-doped NH2-C3N4 / CoAl-LDHs composite material: Measure 50 mL of deionized water into a beaker, add 1 g of the NH2-C3N4 / CoAl-LDHs composite material obtained in Step 4, and ultrasonically disperse until a uniform suspension is formed; add 1~3 wt% palladium chloride, 0.1~0.3 g sodium chloride, and ascorbic acid at 3 times the mass of palladium chloride to the suspension in sequence; add KOH solution dropwise to adjust the pH of the system to 8~9; transfer the mixture to a water bath and react at 50℃ for 8 hours; after the reaction, centrifuge at 8000 r / min to separate and collect the solid product; place the product in a vacuum oven and dry at 60℃ for 18 hours, and grind to obtain the Pd-doped NH2-C3N4 / CoAl-LDHs composite material.

[0008] Furthermore, the dimensions of the polyimide film substrate are 11mm×16mm×0.1mm~15mm×20mm×1mm.

[0009] Furthermore, the Au interdigitated electrode has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.1mm, a finger pair count of 10~50, and an electrode thickness of 0.02μm~0.2μm.

[0010] Furthermore, the dimensions of the rectangular cavity of the copper-clad laminate are 3cm×8cm×3cm to 10cm×10cm×8cm.

[0011] Furthermore, the Bluetooth module is used to transmit the detection data to an external terminal.

[0012] A detection method for a low-power methane sensor includes the following steps: S1. Before detection, first connect the battery to power the system, and at the same time turn on the ultraviolet lamp and preheat for 5 minutes; the external terminal establishes a wireless communication connection with the sensor through the Bluetooth module 10, and then the resistance acquisition chip acquires and records the baseline resistance Ra of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer in the air. S2. After the low-power methane sensor is placed in the methane detection environment, the methane gas rapidly diffuses to the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer and completes adsorption. Under the continuous excitation of ultraviolet light, the adsorbed methane molecules are activated, and the resistance acquisition chip captures the changed resistance signal Rg in real time. Sensor response value according to formula calculate; Combining linear fitting equations Where x is the concentration of methane gas to be measured, in ppm; y is the sensor response value. The concentration x of methane gas is calculated based on the linear fitting equation obtained by y, and the detection data is transmitted to an external terminal via Bluetooth module to realize the quantitative detection of methane concentration. S3. After the detection is completed, the ultraviolet lamp remains on. Continuous ultraviolet light irradiation accelerates the desorption of residual gas on the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer, causing the low-power methane sensor to return to the baseline resistance state, thus meeting the requirement of continuous cyclic detection.

[0013] Furthermore, the recovery time of the low-power methane sensor described in step S3 is 150~200s.

[0014] The beneficial effects of this invention are: This invention discloses a low-power methane sensor detection method. The Pd-doped NH2-C3N4 / CoAl-LDHs nanomaterial layer, with its three-dimensional layered structure, synergistic effect of Pd catalytic sites and heterojunction interfaces, and enhanced by ultraviolet light excitation, efficiently activates and rapidly reacts with methane molecules without high-temperature heating, reducing energy consumption and equipment complexity. For methane gas concentrations in the range of 100ppm to 1000ppm, detection can be completed at room temperature, with a sensor recovery time of <200s. The linear fitting equation for detection is as follows: (x represents the concentration of methane to be measured, in ppm; y represents the sensor response value). The detection limit is as low as 100ppm, the linear correlation coefficient reaches 0.93539, and the detection performance is stable and accurate. The sensor uses a double-layer copper-clad laminate as a substrate, integrates a sensing unit and a data processing module, and is equipped with Bluetooth wireless transmission function to realize portable real-time detection of methane gas, improving the flexibility and applicability of detection scenarios. Attached Figure Description

[0015] Figure 1 This is a perspective view of a low-power methane sensor according to the present invention. Figure 2 The XRD pattern of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material prepared in Example 1; Figure 3 SEM images of Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor materials prepared in Example 1; Figure 4 The dynamic sensing response of the room temperature methane sensor based on Pd-doped NH2-C3N4 / CoAl-LDHs prepared in Example 1 to methane gas from 100ppm to 1000ppm is shown in the figure. Figure 5 The repeatability test diagram of the room temperature methane sensor based on Pd-doped NH2-C3N4 / CoAl-LDHs prepared in Example 1 for 1000ppm methane gas. Figure 6 The linear fitting curve of the response value of the room temperature methane sensor based on Pd-doped NH2-C3N4 / CoAl-LDHs prepared in Example 1 to methane gas at concentrations of 100ppm to 1000ppm is shown. Figure 7 This is a schematic diagram of the structure of the first device of a low-power methane detection sensor according to the present invention; Figure 8 This is a schematic diagram of the structure of the second device of a low-power methane detection sensor according to the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0017] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0018] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 8 Detailed explanation is as follows:

[0019] Example 1: A low-power methane sensor includes a polyimide thin film substrate 1, an Au interdigitated electrode 2, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3, a horizontal pin header 4, a rectangular cavity of a copper-clad laminate 5, a double-row pin header 6, a battery 7, an ultraviolet lamp 8, a resistance acquisition chip 9, and a Bluetooth module 10. The first device comprises a polyimide film substrate 1, an Au interdigitated electrode 2, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3, and a horizontally mounted pin array 4. The Au interdigitated electrode 2 is prepared on the surface of the polyimide film substrate 1 by chemical deposition. The sensing area of ​​the Au interdigitated electrode 2 is uniformly coated with the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3. The leads of the Au interdigitated electrode 2 are connected to the horizontally mounted pin array 4. In the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3, Pd is doped in elemental form in the NH2-C3N4 / CoAl-LDHs composite material at a ratio of 1~3 wt%. The rectangular cavity 5 of the copper-clad laminate, the double-row connector 6, the battery 7, the ultraviolet lamp 8, the resistance acquisition chip 9, and the Bluetooth module 10 constitute the second device. The double-row connector 6, the resistance acquisition chip 9, the Bluetooth module 10, and the battery 7 are installed sequentially from left to right on the bottom plate of the rectangular cavity 5 of the copper-clad laminate. One end of the double-row connector 6 is connected to the resistance acquisition chip 9, and the resistance acquisition chip 9 is connected to the Bluetooth module 10. The ultraviolet lamp 8 is installed on the top plate of the rectangular cavity 5 of the copper-clad laminate. The first device is placed below the ultraviolet lamp 8. The horizontal pin 4 of the first device is connected to the other end of the double-row connector 6. The battery 7 provides overall power for a low-power methane sensor.

[0020] Furthermore, the specific fabrication and assembly process of the low-power methane sensor is as follows: A polyimide film with dimensions of 12mm × 17mm × 0.11mm was selected as the polyimide film substrate, and Au interdigitated electrodes 2 were prepared on its surface by chemical deposition. The Au interdigitated electrodes 2 have a finger width of 0.08mm, a finger spacing of 0.08mm, a finger pair count of 20, a sensing area of ​​7mm × 10mm, and an electrode thickness of 0.02μm. Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material was prepared by ultrasonically dispersing 0.5mg of the material in 5 times its volume of ethanol solution to prepare a suspension. The suspension was uniformly coated onto the sensing area of ​​the Au interdigitated electrodes 2, and the modification of the sensing material was completed after drying at 70℃ for 3h. The XRD pattern of the material is attached. Figure 2 Corresponding to the standard card; SEM images (attached) Figure 3 The device displays a three-dimensional hierarchical layered structure, providing ample gas adsorption channels and active sites. A horizontal pin header 4 is selected and soldered to the lead-out end of the Au interdigital electrode 2, completing the assembly of the first device. A double-layer copper-clad laminate with dimensions of 3cm × 9cm × 1.6mm is selected, and the upper and lower layers are connected by hexagonal copper pillars to form a rectangular cavity 5 (3cm × 9cm × 3cm) of the copper-clad laminate. The components of the data processing module are soldered into the cavity, completing the assembly of the second device. The first device is inserted into the lower interface of the cavity of the second device, so that the horizontal pin header 4 is connected to the double row of female header 6; the battery 7 in the data processing module is a 3.7V lithium battery, the resistance acquisition chip 9 is an ADS1115, the Bluetooth module 10 is a BLE5.0 module, and the ultraviolet lamp 8 is soldered to the cavity directly above the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3 to ensure that the ultraviolet light uniformly illuminates the sensing area; the sensing area of ​​the sensor is open on all sides without obstruction, ensuring that methane gas can freely diffuse to the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material 3.

[0021] Sensor performance test results in this embodiment: Table 1 shows a comparison of the Pd-doped NH2-C3N4 / CoAl-LDO nanosensor material layer described in this embodiment with existing methane detection technologies: Table 1

[0022] The Pd-doped NH2-C3N4 / CoAl-LDO nanosensing material layer described in this embodiment effectively overcomes the performance defects of existing sensitive materials through the innovative structure of layered NH2-C3N4 / CoAl-LDO composite + Pd noble metal doping. Its beneficial effects are as follows: 1. Achieve stable sensing at low concentrations at room temperature, adapting to practical detection scenarios; Compared with existing technologies such as ZnO / Pd@ZIF-8 / 67 (requires 210℃) and rGO / ZnO (requires 350℃) which rely on high-temperature driving, the material of this application can work stably at room temperature (RT) without the need for an additional heating module, which reduces device energy consumption and heat dissipation design costs, and also eliminates safety hazards in high-temperature scenarios; At the same time, the material of this application can achieve response values ​​of 15.7% and 16.9% for low concentration target gases of 100ppm and 200ppm, respectively, perfectly matching the typical concentration range of practical scenarios such as industrial leaks and indoor air quality monitoring, solving the defect of existing room temperature materials (such as 1wt% Au-decorated PbS) that can only respond to high concentration gases.

[0023] 2. Breakthrough in Response Speed ​​for Low-Concentration Room Temperature Sensing: Existing room temperature sensitive materials generally exhibit poor response speeds in low concentration ranges. For example, ZnO nanowires (UV) have a response time of 320s at a target gas concentration of 1000ppm, and 1wt% Au-modified PbS still requires 180s at a high concentration of 20000ppm. In contrast, the material in this application achieves response times of only 57s and 55s at low concentrations of 100ppm and 200ppm, respectively, representing a response speed more than three times faster than similar room temperature materials. This allows for rapid capture of changes in target gas concentration, meeting the needs of real-time monitoring.

[0024] 3. The detection limit is highly compatible with practical needs. The detection limit of the material in this application is 100 ppm, which is consistent with the superior performance of ZnO / Pd@ZIF-8 / 67 and ZnO nanosheets (UV) in the prior art. However, unlike the limitations of the above materials that are driven by high temperature or have high concentration response, the material in this application can reach this detection limit under practical conditions of room temperature and low concentration, without sacrificing energy consumption or adapting to high concentration scenarios, thus significantly improving its practicality and adaptability.

[0025] 4. Performance Balance Fills the Gap in Existing Technologies Existing sensitive materials suffer from performance contradictions such as high response at high temperatures but high energy consumption, low response at room temperature and slow speed, and high response at high concentrations but failure at low concentrations. However, the material in this application achieves a performance balance of room temperature operation, low concentration response, and fast response through structural innovation, effectively filling the gap in existing technologies in the field of low energy consumption and low concentration sensing, and has a broader prospect for commercial application.

[0026] As attached Figure 4 As shown, within the methane concentration range of 100ppm to 1000ppm, the sensor exhibits significant response characteristics to methane gas, and the response value shows a stable increasing trend with increasing methane concentration, demonstrating good concentration dependence. (See attached image) Figure 5Repeatability test results show that, after five consecutive cycles of detection in a 1000 ppm methane atmosphere, the fluctuation range of the sensor's response value is less than 5%, fully demonstrating that the sensor possesses excellent detection stability and reliability. (Appendix) Figure 6 The linear fitting curve further shows that the linear correlation coefficient R of this detection system is... 2 The linearity is 0.93539, indicating good linearity, and the detection limit is as low as 100 ppm, which can fully meet the early warning and monitoring needs of low-concentration methane leaks.

[0027] Example 2: A low-power methane sensor includes a polyimide thin film substrate 1, an Au interdigitated electrode 2, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3, a horizontal pin header 4, a rectangular cavity of a copper-clad laminate 5, a double-row pin header 6, a battery 7, an ultraviolet lamp 8, a resistance acquisition chip 9, and a Bluetooth module 10. The first device consists of a polyimide film substrate 1, an Au interdigitated electrode 2, a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3, and a horizontally mounted pin array 4. The Au interdigitated electrode 2 is prepared on the upper surface of the polyimide film substrate 1 by chemical deposition. The Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3 is uniformly coated on the sensing area of ​​the Au interdigitated electrode 2. The lead-out end of the Au interdigitated electrode 2 is connected to the horizontally mounted pin array 4. The rectangular cavity 5 of the copper-clad laminate, the double-row connector 6, the battery 7, the ultraviolet lamp 8, the resistance acquisition chip 9, and the Bluetooth module 10 constitute the second device. The double-row connector 6, the resistance acquisition chip 9, the Bluetooth module 10, and the battery 7 are installed sequentially from left to right on the bottom plate of the rectangular cavity 5 of the copper-clad laminate. One end of the double-row connector 6 is connected to the resistance acquisition chip 9, and the resistance acquisition chip 9 is connected to the Bluetooth module 10. The ultraviolet lamp 8 is installed on the top plate of the rectangular cavity 5 of the copper-clad laminate. The first device is placed below the ultraviolet lamp 8. The horizontal pin 4 of the first device is connected to the other end of the double-row connector 6. The battery 7 provides overall power for a low-power methane sensor.

[0028] Furthermore, based on the area of ​​the sensing region being 5mm×10mm~10mm×20mm, the coating mass of the nanosensing material in the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer 3 is set to be 0.5mg~50mg.

[0029] Furthermore, the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material has a nanoscale three-dimensional layered structure with a specific surface area of ​​10 m². 2 / g~50m 2 / g.

[0030] Furthermore, the preparation method of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 5 degrees Celsius / minute, and calcine at a constant temperature of 500°C for 4 hours in an air atmosphere; after the muffle furnace cools naturally to room temperature, take out the calcined product, grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4 for later use; Step 2. Amine-modified carbon nitride, NH 2- Preparation of C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker, stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the above mixed solvent, sonicate until the powder is completely dispersed; transfer the dispersion to a three-necked flask, place it in a 90℃ constant temperature oil bath, and react at a constant temperature for 12 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven, dry it at 60℃ for 24 hours, grind it after drying, and collect the NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.2333 g of cobalt nitrate hexahydrate, 0.15 g of aluminum nitrate nonahydrate, 0.15 g of ammonium fluoride, and 1.7 g of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in a forced-air drying oven. Heat at 90°C for 6 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60°C for 24 hours. Collect the CoAl-LDHs powder for later use. Step 4. Preparation of NH2-C3N4 / CoAl-LDHs composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder and 1 g of CoAl-LDH powder in sequence, and then add 0.03 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 2 hours to ensure that the two materials are fully composited; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min; collect the solid product after centrifugation, put it in a vacuum oven, dry it at 60℃ for 24 hours, grind it to obtain the NH2-C3N4 / CoAl-LDHs composite material for later use; Step 5. Preparation of Pd-doped NH2-C3N4 / CoAl-LDHs composite material: 50 mL of deionized water was measured into a beaker, and 1 g of the NH2-C3N4 / CoAl-LDHs composite material obtained in Step 4 was added. The mixture was ultrasonically dispersed until a uniform suspension was formed. 2 wt% palladium chloride and ascorbic acid (3 times the mass of palladium chloride) were added to the suspension in sequence. KOH solution was added dropwise to adjust the pH of the system to 8-9. The mixture was transferred to a water bath and reacted at 50℃ for 8 hours. After the reaction, the solid product was collected by centrifugation at 8000 r / min. The product was placed in a vacuum oven and dried at 60℃ for 24 hours. After grinding, the Pd-doped NH2-C3N4 / CoAl-LDHs composite material was obtained.

[0031] Furthermore, the dimensions of the polyimide film substrate 1 are 11mm×16mm×0.1mm~15mm×20mm×1mm.

[0032] Furthermore, the Au interdigitated electrode 2 has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.1mm, a finger pair count of 10~50, and an electrode thickness of 0.02μm~0.2μm.

[0033] Furthermore, the dimensions of the rectangular cavity 5 of the copper-clad laminate are 3cm×8cm×3cm to 10cm×10cm×8cm.

[0034] Furthermore, the Bluetooth module 10 is used to transmit the detection data to an external terminal.

[0035] Example 3: The detection method of a low-power methane sensor according to Example 1 includes the following steps: S1. Before detection, first connect the battery to power the system, and at the same time turn on the ultraviolet lamp and preheat for 5 minutes; the external terminal establishes a wireless communication connection with the sensor through the Bluetooth module 10, and then the resistance acquisition chip acquires and records the baseline resistance Ra of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer in the air. S2. After the low-power methane sensor is placed in the methane detection environment, the methane gas rapidly diffuses to the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer and completes adsorption. Under the continuous excitation of ultraviolet light, the adsorbed methane molecules are activated, and the resistance acquisition chip captures the changed resistance signal Rg in real time. Sensor response value according to formula calculate; Combining linear fitting equations Where x is the concentration of methane gas to be measured, in ppm; y is the sensor response value. The concentration x of methane gas is calculated based on the linear fitting equation obtained by y, and the detection data is transmitted to an external terminal via Bluetooth module to realize the quantitative detection of methane concentration. S3. After the detection is completed, the ultraviolet lamp remains on. Continuous ultraviolet light irradiation accelerates the desorption of residual gas on the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer, causing the low-power methane sensor to return to the baseline resistance state, thus meeting the requirement of continuous cyclic detection.

[0036] Furthermore, the recovery time of the low-power methane sensor described in step S3 is 150~200s.

[0037] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0038] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A low-power methane sensor, characterized in that, Includes a polyimide film substrate (1), Au interdigitated electrodes (2), Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3), horizontal pin header (4), copper-clad laminate rectangular cavity (5), double-row pin header (6), battery (7), ultraviolet lamp (8), resistance acquisition chip (9), and Bluetooth module (10). The first device consists of a polyimide film substrate (1), an Au interdigitated electrode (2), a Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3), and a horizontal pin header (4). The Au interdigitated electrode (2) is prepared on the surface of the polyimide film substrate (1) by chemical deposition. A Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3) is uniformly coated on the sensing area of ​​the Au interdigitated electrode (2). The leads of the Au interdigitated electrode (2) are connected to the horizontal pin header (4). In the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3), Pd is doped in elemental form in the NH2-C3N4 / CoAl-LDHs composite material at a ratio of 1~3 wt%. The copper-clad laminate rectangular cavity (5), double-row connector (6), battery (7), ultraviolet lamp (8), resistance acquisition chip (9), and Bluetooth module (10) constitute the second device; the double-row connector (6), resistance acquisition chip (9), Bluetooth module (10), and battery (7) are installed from left to right on the bottom plate of the copper-clad laminate rectangular cavity (5), one end of the double-row connector (6) is connected to the resistance acquisition chip (9), and the resistance acquisition chip (9) is connected to the Bluetooth module (10); the ultraviolet lamp (8) is installed on the top plate of the copper-clad laminate rectangular cavity (5); the first device is placed below the ultraviolet lamp (8), the horizontal pin (4) of the first device is connected to the other end of the double-row connector (6), and the battery (7) provides overall power for a low-power methane sensor.

2. The low-power methane sensor according to claim 1, characterized in that, Based on the sensing area of ​​5mm×10mm~10mm×20mm, the coating mass of the nanosensing material in the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer (3) is set to be 0.5mg~50mg.

3. A low-power methane sensor according to claim 2, characterized in that, The Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material has a nanoscale three-dimensional layered structure with a specific surface area of ​​10 m². 2 / g~50m 2 / g.

4. A low-power methane sensor according to claim 3, characterized in that, The preparation method of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material includes the following steps: Step 1. Preparation of graphitic carbon nitride C3N4: Take a certain mass of melamine and spread it evenly in a porcelain boat; put the porcelain boat into a muffle furnace, set the heating rate to 1 degree Celsius / minute, and calcine at a constant temperature of 500°C for 4 hours in an air atmosphere; after the muffle furnace cools naturally to room temperature, take out the calcined product, grind it thoroughly into a fine powder with a mortar and pestle to obtain graphitic carbon nitride C3N4 for later use; Step 2. Amine-modified carbon nitride (NH4N) 2- Preparation of C3N4: Measure 30 mL of ammonia water and 90 mL of anhydrous ethanol into a beaker, stir evenly to prepare a mixed solvent; weigh 1 g of C3N4 powder obtained in step 1 and add it to the above mixed solvent, sonicate until the powder is completely dispersed; transfer the dispersion to a three-necked flask, place it in a 90℃ constant temperature oil bath, and react at a constant temperature for 12 hours; after the reaction is completed, cool to room temperature and perform vacuum filtration; place the filter cake in a vacuum oven, dry it at 60℃ for 24 hours, grind it after drying, and collect the NH2-C3N4 powder for later use; Step 3. Preparation of CoAl-LDHs: Weigh 0.2333 g of cobalt nitrate hexahydrate, 0.15 g of aluminum nitrate nonahydrate, 0.15 g of ammonium fluoride, and 1.7 g of urea, and add them sequentially to a beaker containing 35 mL of deionized water. Stir magnetically for 1 hour until all solid reagents are completely dissolved, forming a clear and transparent precursor solution. Transfer the precursor solution to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in a forced-air drying oven. Heat at a constant temperature of 90℃~120℃ for 6 hours. After the reaction is complete, allow the reactor to cool naturally to room temperature, open the reactor, and perform vacuum filtration. Place the filter cake in a vacuum oven and dry at 60℃ for 24 hours. Collect the CoAl-LDHs powder for later use. Step 4. Preparation of NH2-C3N4 / CoAl-LDHs composite material: Measure 50 mL of deionized water into a beaker, add 0.5 g of NH2-C3N4 powder and 1 g of CoAl-LDHs powder in sequence, and then add 0.03 g of polyvinylpyrrolidone; sonicate until the powder is completely dispersed, and then magnetically stir for 2 hours to ensure that the two materials are fully composited; transfer the mixture to a centrifuge tube and centrifuge at 8000 r / min. The solid product after centrifugation was collected, placed in a vacuum oven, dried at 60°C for 24 hours, and then ground to obtain the NH2-C3N4 / CoAl-LDHs composite material for later use. Step 5. Preparation of Pd-doped NH2-C3N4 / CoAl-LDHs composite material: Measure 50 mL of deionized water into a beaker, add 1 g of the NH2-C3N4 / CoAl-LDHs composite material obtained in step 4, and ultrasonically disperse until a uniform suspension is formed; add 1~3 wt% palladium chloride, 0.1~0.3 g sodium chloride, and ascorbic acid at 3 times the mass of palladium chloride to the suspension in sequence; add KOH solution dropwise to adjust the pH of the system to 8~9; transfer the mixture to a water bath and react at 50℃ for 8 hours; after the reaction, centrifuge at 8000 r / min to separate and collect the solid product; place the product in a vacuum oven and dry at 60℃ for 18 hours, and grind to obtain the Pd-doped NH2-C3N4 / CoAl-LDHs composite material.

5. A low-power methane sensor according to claim 4, characterized in that, The polyimide film substrate (1) has dimensions of 11mm×16mm×0.1mm~15mm×20mm×1mm.

6. A low-power methane sensor according to claim 5, characterized in that, The Au interdigitated electrode (2) has a finger width of 0.05mm~0.5mm, a finger spacing of 0.05mm~0.1mm, a finger pair number of 10~50, and an electrode thickness of 0.02μm~0.2μm.

7. A low-power methane sensor according to claim 6, characterized in that, The dimensions of the rectangular cavity (5) of the copper-clad laminate are 3cm×8cm×3cm~10cm×10cm×8cm.

8. A low-power methane sensor according to claim 7, characterized in that, The Bluetooth module (10) is used to transmit the detection data to an external terminal.

9. A detection method for a low-power methane sensor according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Before detection, first connect the battery to power the system, and at the same time turn on the ultraviolet lamp and preheat for 5 minutes; the external terminal establishes a wireless communication connection with the sensor through the Bluetooth module (10), and then the resistance acquisition chip acquires and records the baseline resistance Ra of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensing material layer in the air. S2. After the low-power methane sensor is placed in the methane detection environment, the methane gas rapidly diffuses to the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer and completes adsorption. Under the continuous excitation of ultraviolet light, the adsorbed methane molecules are activated, and the resistance acquisition chip captures the changed resistance signal Rg in real time. Sensor response value according to formula calculate; Combining linear fitting equations , where x is the concentration of methane gas to be measured in ppm; y is the sensor response value. The concentration x of methane gas is calculated based on the linear fitting equation obtained by y, and the detection data is transmitted to the external terminal via Bluetooth module (10) to realize the quantitative detection of methane concentration; S3. After the detection is completed, the ultraviolet lamp remains on. Continuous ultraviolet light irradiation accelerates the desorption of residual gas on the surface of the Pd-doped NH2-C3N4 / CoAl-LDHs nanosensor material layer, causing the low-power methane sensor to return to the baseline resistance state, thus meeting the requirement of continuous cyclic detection.

10. The detection method of a low-power methane sensor according to claim 9, characterized in that, The recovery time of the low-power methane sensor described in step S3 is 150~200s.

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