Rainfall monitoring sensor based on MXene flexible composite material and preparation method thereof

Abstract

The invention discloses a rainfall monitoring sensor based on an MXene flexible composite material, which comprises a sensing layer arranged on a sensor shell, and is characterized in that the sensing layer comprises an MXene fold sensing layer, and the MXene fold sensing layer is deposited on a substrate layer; a plurality of hydrophobic micro grooves are formed in the surface of the substrate layer; the MXene fold sensing layer comprises an interdigital electrode and an MXene fold layer covering the interdigital electrode, and a dielectric material layer is arranged on the interdigital electrode; the MXene wrinkle sensing layer and the substrate layer are compounded, piezoresistance detection is achieved, the sensor is suitable for smart cities, agricultural irrigation and geological disaster early warning systems, and the technical defects that a traditional rain gauge is prone to blockage and low in precision are overcome.

Description

Technical Field

[0001] The present invention belongs to the field of environmental monitoring and flexible electronic technology, and specifically relates to a rainfall monitoring sensor based on a MXene flexible composite material and a preparation method thereof. Background Art

[0002] The measurement accuracy of mechanical rain gauges (such as tipping bucket sensors, such as the BOY-YL05-1 tipping bucket rain gauge) is limited by their environment and structure. Water may still enter the funnel during the tipping process, leading to errors in the calculation of the water volume per single tipping, affecting the cumulative accuracy. During heavy rain, the limited tipping frequency of the bucket can easily underestimate the rainfall intensity. During light rain, insufficient water volume cannot trigger a tipping, resulting in missed measurements or delayed measurements. They are susceptible to interference from natural factors: fluctuations in precipitation intensity, strong winds, hail, and other extreme weather conditions can affect the balance of the bucket, exacerbating errors. They require high maintenance and are prone to clogging. The funnel-shaped collector has a large inlet and a small outlet, making it easily clogged by leaves, dust, insects, or mud, requiring frequent cleaning to maintain proper operation. Equipment that has not been maintained for a long time has a significantly increased failure rate. Lack of real-time performance: The water volume counted by the bucket often comes from previously collected rainwater, rather than real-time precipitation. This results in delayed rainfall intensity data that fails to reflect instantaneous rainfall changes. Environmental adaptability is limited. In low-temperature environments, accumulated water in the collector may freeze, causing the bucket to be unable to flip normally. Strong vibration or tilted installation may also affect measurement stability. It relies on a mechanical structure and is easily blocked by sand and dust, resulting in poor long-term stability and inability to detect small rainfall (<0.1mm / h).

[0003] Optical sensors (L301 optical rain sensor, which uses infrared optical detection principles and has no mechanical components) are relatively expensive and require stringent technical requirements. Their manufacturing and maintenance costs are significantly higher than those of traditional sensors, and they place high demands on production processes and technology, limiting their widespread adoption. They lack sensitivity for monitoring light rainfall. When raindrops are sparse or the rainfall is minimal, the sensor may not respond in a timely manner due to weak signals or a lack of raindrop coverage in the sensing area, leading to missed detections or delays. They are susceptible to environmental interference and dust / stains. If the sensor surface is obscured by dust, snow, or stains, abnormal light refraction may lead to misjudgments or decreased sensitivity. Light dependence: Some optical sensors may experience changes in light intensity, affecting detection stability in strong or low light conditions. The sensor also has a limited sensing area. The sensor's small sensing area can only monitor rainfall distribution in a local area, potentially leading to missed detections due to raindrops not covering the sensing area. It is subject to significant interference from ambient light, resulting in low raindrop recognition accuracy and high maintenance costs.

[0004] Piezoelectric sensors (piezoelectric rain sensor PH-1X-001, using piezoelectric ceramic kinetic energy to monitor rainfall, identifying according to the force of falling raindrops) are sensitive to humid environments. Some piezoelectric materials are easily affected by humidity, and moisture-proof measures need to be taken to avoid performance degradation. The output current response is poor, and the output signal needs to rely on a charge amplifier or a high input impedance circuit for optimization, otherwise the measurement accuracy may be affected. When the rainfall is very small or there are no raindrops on the surface of the sensor, it may not respond or not work actively, resulting in missed measurements. The cost is relatively high, and its manufacturing and maintenance costs are usually higher. Environmental adaptability limitations. Although the design reduces external interference (such as leaves and dust), extreme weather or special environments (such as strong winds and hail) may still require additional protection or calibration. The sensitivity is limited, and the rigid substrate is difficult to adapt to complex installation environments. Summary of the Invention

[0005] The object of the present invention is to provide a display to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a rainfall monitoring sensor based on a MXene flexible composite material, comprising a sensing layer provided in a sensor housing, wherein:

[0007] The sensing layer includes a MXene wrinkle sensing layer, and the MXene wrinkle sensing layer is deposited on a base layer;

[0008] The surface of the base layer is provided with a plurality of hydrophobic micro grooves;

[0009] The MXene wrinkle sensing layer includes interdigitated electrodes and a MXene wrinkle layer covering the interdigitated electrodes, and a dielectric material layer is provided on the interdigitated electrodes.

[0010] Preferably, the MXene wrinkle layer is composed of multiple layers of nanosheets stacked from bottom to top to form a wrinkle structure.

[0011] Preferably, the MXene wrinkle layer will undergo elastic deformation under external force impact.

[0012] Preferably, a positive electrode and a negative electrode are provided on the MXene wrinkle sensing layer.

[0013] Another object of the present invention is to provide a method for preparing a rainfall monitoring sensor based on a MXene flexible composite material, which comprises the following steps:

[0014] Step 1: MXene etching: adding MXene etching solution to Ti3AlC2, ultrasonic exfoliation, and freeze drying to obtain MXene nanopowder;

[0015] Step 2: forming a substrate, taking a silicon template with a micro-groove structure on the surface, spin-coating a PDMS prepolymer on the silicon template, and peeling it off after curing to form a substrate with a wrinkled structure;

[0016] Step 3: Prepare the PVDF-TrFE-MXene sensing layer by spin coating. A single-layer MXene dispersion is applied to the PDMS substrate by a spin coater to form a MXene wrinkle layer. A PVDF-TrFE solution is applied to the interdigitated electrodes by a spin coater to form a dielectric material layer. The interdigitated electrodes are then placed on the MXene wrinkle layer. A single-layer MXene dispersion is applied to the dielectric material layer by a spin coater to form a MXene wrinkle layer.

[0017] Step 4: Assemble the sensor, fix the sensing layer to the sensor housing, and connect the acquisition device to the sensing layer for data monitoring.

[0018] In the present invention, the MXene etching MAX precursor material is Ti3AIC2.

[0019] In the present invention, the dielectric material is PVDF-TrFE.

[0020] Preferably, step 1 specifically comprises the following steps:

[0021] Step 1.1: Mix LiF and hydrochloric acid, heat and stir in an oil bath, then add Ti3AlC2, stir magnetically and react;

[0022] Step 1.2, centrifuging the mixed solution obtained in step 1.1, adding a mixed solution of LiCl and deionized water, letting it stand and then centrifuging again;

[0023] Step 1.3: freeze-dry the sample after centrifugation to obtain MXene nanopowder.

[0024] Preferably, step 2 specifically includes the following steps:

[0025] Step 2.1, taking a silicon template with a hydrophobic micro-groove structure on its surface and cutting it to size;

[0026] Step 2.2, spin-coating the PDMS prepolymer onto the silicon template using a spin coater;

[0027] Step 2.3: peeling off after curing to form a base with a wrinkled structure.

[0028] Preferably, step 3 specifically includes the following steps:

[0029] Step 3.1, prepare MXene nanopowder into a monolayer MXene dispersion, and ultrasonically stir to uniformly disperse the MXene in the solution;

[0030] Step 3.2: Drop the MXene dispersion onto the PDMS substrate and use a spin coater to form a MXene wrinkle layer on the substrate.

[0031] Step 3.3: Place the interdigitated electrodes on the MXene wrinkle layer and vacuum dry them.

[0032] Step 3.4, dissolving PVDF-TrFE in NMP organic solvent to prepare a PVDF-TrFE dispersion, and magnetically stirring to uniformly disperse the PVDF-TrFE in the organic solvent;

[0033] Step 3.6: drop a PVDF-TrFE dispersion onto the surface of the interdigitated electrode, and then use a spin coater to form a dielectric material layer on the interdigitated electrode, and then vacuum dry.

[0034] Step 3.7, drop the MXene dispersion onto the dielectric material layer, and use a spin coater to form a MXene wrinkle layer on the dielectric material layer.

[0035] Step 3.8: Vacuum dry the substrate together to obtain the PVDF-TrFE-MXene sensing layer.

[0036] Preferably, the MXene etching solution is a mixed solution of LiF and hydrochloric acid.

[0037] Preferably, the concentration of MXene nanopowder in the monolayer MXene dispersion is 5 mg / ml.

[0038] Technical effects and advantages of the present invention:

[0039] 1. It can detect rainfall intensity and accumulated rainfall in real time with high precision. It uses a composite MXene wrinkle sensing layer and a base layer to achieve piezoresistive detection. It is suitable for smart cities, agricultural irrigation, and geological disaster early warning systems, overcoming the technical shortcomings of traditional rain gauges such as easy clogging and low accuracy.

[0040] 2. By setting up the MXene wrinkle layer, the sensing layer can form a micron-scale wrinkle structure, enhancing the raindrop collision response and improving the detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the present invention;

[0042] Figure 2 Schematic diagram of the sensing layer of the present invention;

[0043] Figure 3 Schematic diagram of the MXene wrinkle sensing layer of the present invention;

[0044] Figure 4 Schematic diagram of the base layer of the present invention;

[0045] Figure 5 The process flow for preparing the sensing layer of the present invention is as follows;

[0046] Figure 6 This is the performance test curve of the present invention.

[0047] In the picture:

[0048] 1. Sensor housing; 2. Sensing layer;

[0049] 21. Positive electrode; 22. Negative electrode; 24. MXene wrinkle sensing layer; 25. Base layer; 66. Hydrophobic microgrooves. DETAILED DESCRIPTION

[0050] The following is a combination of the embodiments of the present invention Figure 1-6 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0051] The present invention provides Figure 1-Figure 4 A rainfall monitoring sensor based on a MXene flexible composite material shown in FIG includes a sensing layer 2 provided in a sensor housing 1, wherein:

[0052] The sensing layer 2 includes a MXene wrinkle sensing layer 24, and the MXene wrinkle sensing layer 24 is deposited on a base layer 25;

[0053] The surface of the base layer 25 is provided with a plurality of hydrophobic micro grooves 26;

[0054] The MXene wrinkle sensing layer 24 includes interdigitated electrodes and a MXene wrinkle layer covering the interdigitated electrodes, and a dielectric material layer is provided on the interdigitated electrodes.

[0055] Specifically, the MXene wrinkle layer is composed of multiple layers of nanosheets stacked from bottom to top to form a wrinkle structure.

[0056] Specifically, the MXene wrinkle layer will undergo elastic deformation under external force impact.

[0057] Specifically, the MXene wrinkle sensing layer 24 is provided with an anode electrode 21 and a cathode electrode 22 .

[0058] Another object of the present invention is to provide Figure 5A method for preparing a rainfall monitoring sensor based on a MXene flexible composite material is shown in the figure, wherein the method comprises the following steps:

[0059] Step 1: MXene etching: adding MXene etching solution to Ti3AlC2, ultrasonic exfoliation, and freeze drying to obtain MXene nanopowder;

[0060] Step 2: forming a substrate, taking a silicon template with a micro-groove structure on the surface, spin-coating a PDMS prepolymer on the silicon template, and peeling it off after curing to form a substrate with a wrinkled structure;

[0061] Step 3: Prepare the PVDF-TrFE-MXene sensing layer by spin coating. A single-layer MXene dispersion is applied to the PDMS substrate by a spin coater to form a MXene wrinkle layer. A PVDF-TrFE solution is applied to the interdigitated electrodes by a spin coater to form a dielectric material layer. The interdigitated electrodes are then placed on the MXene wrinkle layer. A single-layer MXene dispersion is applied to the dielectric material layer by a spin coater to form a MXene wrinkle layer.

[0062] Step 4: Assemble the sensor, fix the sensing layer (2) to the sensor housing (1), and connect the acquisition device to the sensing layer (2) to monitor data.

[0063] Specifically, step 1 includes the following steps:

[0064] Step 1.1: Mix LiF and hydrochloric acid, heat and stir in an oil bath, then add Ti3AlC2, stir magnetically and react;

[0065] Step 1.2, centrifuging the mixed solution obtained in step 1.1, adding a mixed solution of LiCl and deionized water, letting it stand and then centrifuging again;

[0066] Step 1.3: freeze-dry the sample after centrifugation to obtain MXene nanopowder.

[0067] Specifically, step 2 includes the following steps:

[0068] Step 2.1, taking a silicon template with a hydrophobic micro-groove structure on its surface and cutting it to size;

[0069] Step 2.2, spin-coating the PDMS prepolymer onto the silicon template using a spin coater;

[0070] Step 2.3: peeling off after curing to form a base with a wrinkled structure.

[0071] Specifically, step 3 includes the following steps:

[0072] Step 3.1, prepare MXene nanopowder into a monolayer MXene dispersion, and ultrasonically stir to uniformly disperse the MXene in the solution;

[0073] Step 3.2: Drop the MXene dispersion onto the PDMS substrate and use a spin coater to form a MXene wrinkle layer on the substrate.

[0074] Step 3.3: Place the interdigitated electrodes on the MXene wrinkle layer and vacuum dry them.

[0075] Step 3.4, dissolving PVDF-TrFE in NMP organic solvent to prepare a PVDF-TrFE dispersion, and magnetically stirring to uniformly disperse the PVDF-TrFE in the organic solvent;

[0076] Step 3.6: drop a PVDF-TrFE dispersion onto the surface of the interdigitated electrode, and then use a spin coater to form a dielectric material layer on the interdigitated electrode, and then vacuum dry.

[0077] Step 3.7, drop the MXene dispersion onto the dielectric material layer, and use a spin coater to form a MXene wrinkle layer on the dielectric material layer.

[0078] Step 3.8: Vacuum dry the substrate together to obtain the PVDF-TrFE-MXene sensing layer.

[0079] Specifically, the MXene etching solution is a mixed solution of LiF and hydrochloric acid.

[0080] Specifically, the concentration of MXene nanopowder in the single-layer MXene dispersion is 5 mg / ml.

[0081] Example:

[0082] See also Figure 1 In the present invention, four mounting holes are provided on the sensor housing 1 to facilitate the installation of the sensor, and the sensing layer 2 is provided above the sensor housing 1 .

[0083] See also Figure 2 and Figure 3 The sensing layer 2 includes a MXene wrinkle sensing layer 24 , and the MXene wrinkle sensing layer 24 is deposited on a base layer 25 ; and an electrode positive electrode 21 and an electrode negative electrode 22 are provided on the MXene wrinkle sensing layer 24 .

[0084] In the present invention, the MXene wrinkle layer is composed of multiple layers of nanosheets stacked from bottom to top to form a wrinkle structure.

[0085] See also Figure 4 The base layer 25 is made of PDMS with a thickness of 500 μm, and a plurality of hydrophobic micro grooves 26 are provided on the top surface of the base layer 25 . The hydrophobic micro grooves 26 are provided with a spacing of 50 μm, a width of 20 μm, and a depth of 30 μm.

[0086] See also Figure 5 , the sensor preparation steps are as follows:

[0087] Step 1, MXene etching, step 1.1, after mixing LiF and 9M hydrochloric acid, heating and stirring in an oil bath, add Ti3AlC2 (MAX precursor material), magnetically stir and react; step 1.2, the mixed solution obtained in step 1.1 is centrifuged, and a mixed solution of LiCl and deionized water is added, and the mixture is allowed to stand and then centrifuged again; step 1.3, the sample after centrifugation is freeze-dried to obtain MXene nanopowder.

[0088] Step 2: forming the substrate. Step 2.1: taking a substrate having a surface with a hydrophobic micro-groove 26 structure (the hydrophobic micro-groove structure is as shown in FIG. Figure 4 ) is cut to size, and the cutting size is 50×50 mm2; step 2.2, PDMS prepolymer is spin-coated on the silicon template by a spin coater; step 2.3, after curing, it is peeled off to form a substrate with a wrinkled structure.

[0089] Step 3, PVDF-TrFE-MXene sensing layer spin coating preparation, step 3.1, MXene nanopowder (prepared in step 1) is prepared into a 5 mg / ml single-layer MXene dispersion, 300W ultrasonic stirring for 6 hours, so that MXene is evenly dispersed in the solution, and the amount of MXene added is between 1% and 10% (mass fraction); step 3.2, the MXene dispersion is dropped on the PDMS substrate, and the spin coater is used to spin coat at a speed of 3000 rpm for 120 seconds to form a uniform thin film on the substrate. In this way, the MXene dispersion will form a MXene wrinkle layer on the substrate; step 3.3, the interdigitated electrode is placed on The MXene wrinkle layer is placed in a vacuum dryer together with the substrate and vacuum dried at 60°C for 6 hours; step 3.4, PVDF-TrFE is dissolved in NMP organic solvent to prepare a PVDF-TrFE dispersion with a mass fraction of 10%-20%, and magnetic stirring is performed for 1 hour to uniformly disperse PVDF-TrFE in the organic solvent; step 3.6, the PVDF-TrFE dispersion is dropped on the surface of the interdigitated electrode, and the PVDF-TrFE dispersion is spin-coated at a speed of 3000 rpm for 120 seconds using a spin coater to form a dielectric material layer on the interdigitated electrode, and the substrate is placed in a vacuum dryer together with the substrate and vacuum dried at 60°C for 6 hours;

[0090] Step 3.7: Drop the MXene dispersion onto the dielectric material layer and spin coat it at 3000 rpm for 120 seconds to form a MXene wrinkle layer on the dielectric material layer.

[0091] Step 3.8: Place the substrate together with the substrate in a vacuum dryer and vacuum dry at 60°C for 6 hours to obtain a PVDF-TrFE-MXene sensing layer.

[0092] Step 4: Sensor assembly, see Figure 1 , fix the sensing layer 2 to the sensor housing 1, connect the electrode positive electrode 21 and the electrode negative electrode 22 with a gold wire with a diameter of 0.025 mm, connect the electrode wiring to the terminal, the positive electrode to the electrode positive electrode 21, the negative electrode to the electrode negative electrode 22, and monitor the data through the acquisition equipment.

[0093] Measured data: see Figure 6 The red curve is the relationship between the impact force of raindrops on the sensor surface and the sensor deformation, and the blue curve is the relationship between the sensor deformation rate and resistance.

[0094] Working principle:

[0095] The detection mechanism adopts a piezoresistive mode. The impact of raindrops causes the MXene wrinkle sensing layer 24 to deform, causing the resistance to change, thereby achieving the detection effect. In addition, by depositing single or multi-layer nanosheets (thickness 1-5nm) on the flexible substrate layer 25 (PDMS / hydrogel), a sensing layer 2 with a micron-scale wrinkle structure is formed. This can form a micron-scale wrinkle structure in the sensing layer, enhance the raindrop collision response, and improve the detection sensitivity.

[0096] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rainfall monitoring sensor based on a MXene flexible composite material, comprising a sensing layer (2) provided in a sensor housing (1), characterized in that: The sensing layer (2) includes a MXene wrinkle sensing layer (24), and the MXene wrinkle sensing layer (24) is deposited on a base layer (25); The surface of the base layer (25) is provided with a plurality of hydrophobic micro grooves (26); The MXene wrinkle sensing layer (24) comprises interdigitated electrodes and a MXene wrinkle layer covering the interdigitated electrodes, and a dielectric material layer is provided on the interdigitated electrodes.

2. The rainfall monitoring sensor based on the MXene flexible composite material according to claim 1, characterized in that: The MXene wrinkle layer is composed of multiple layers of nanosheets stacked from bottom to top to form a wrinkle structure.

3. The rainfall monitoring sensor based on MXene flexible composite material according to claim 1, characterized in that: The MXene wrinkle layer will undergo elastic deformation under external force impact.

4. The rainfall monitoring sensor based on the MXene flexible composite material according to claim 1, characterized in that: An electrode positive electrode (21) and an electrode negative electrode (22) are provided on the MXene wrinkle sensing layer (24).

5. A method for preparing a rainfall monitoring sensor based on MXene flexible composite material, characterized in that: The following steps are included: Step 1: MXene etching: adding MXene etching solution to Ti3AlC2, ultrasonic exfoliation, and freeze drying to obtain MXene nanopowder; Step 2: forming a substrate, taking a silicon template with a micro-groove structure on the surface, spin-coating a PDMS prepolymer on the silicon template, and peeling it off after curing to form a substrate with a wrinkled structure; Step 3: Prepare the PVDF-TrFE-MXene sensing layer by spin coating. A single-layer MXene dispersion is applied to the PDMS substrate by a spin coater to form a MXene wrinkle layer. A PVDF-TrFE solution is applied to the interdigitated electrodes by a spin coater to form a dielectric material layer. The interdigitated electrodes are then placed on the MXene wrinkle layer. A single-layer MXene dispersion is applied to the dielectric material layer by a spin coater to form a MXene wrinkle layer. Step 4: Assemble the sensor, fix the sensing layer (2) to the sensor housing (1), and connect the acquisition device to the sensing layer (2) for data monitoring.

6. The method for preparing a rainfall monitoring sensor based on a MXene flexible composite material according to claim 5, characterized in that: Step 1 specifically includes the following steps: Step 1.1: Mix LiF and hydrochloric acid, heat and stir in an oil bath, then add Ti3AlC2, stir magnetically and react; Step 1.2, centrifuging the mixed solution obtained in step 1.1, adding a mixed solution of LiCl and deionized water, letting it stand and then centrifuging again; Step 1.3: freeze-dry the sample after centrifugation to obtain MXene nanopowder.

7. The method for preparing a rainfall monitoring sensor based on a MXene flexible composite material according to claim 5, characterized in that: Step 2 specifically includes the following steps: Step 2.1, taking a silicon template having a hydrophobic micro-groove (66) structure on its surface and cutting it to size; Step 2.2, spin-coating the PDMS prepolymer onto the silicon template using a spin coater; Step 2.3: peeling off after curing to form a base with a wrinkled structure.

8. The method for preparing a rainfall monitoring sensor based on a MXene flexible composite material according to claim 5, characterized in that: Step 3 specifically includes the following steps: Step 3.1, prepare MXene nanopowder into a monolayer MXene dispersion, and ultrasonically stir to uniformly disperse the MXene in the solution; Step 3.2: Drop the MXene dispersion onto the PDMS substrate and use a spin coater to form a MXene wrinkle layer on the substrate. Step 3.3: Place the interdigitated electrodes on the MXene wrinkle layer and vacuum dry them. Step 3.4, dissolving PVDF-TrFE in NMP organic solvent to prepare a PVDF-TrFE dispersion, and magnetically stirring to uniformly disperse the PVDF-TrFE in the organic solvent; Step 3.6: drop a PVDF-TrFE dispersion onto the surface of the interdigitated electrode, and then use a spin coater to form a dielectric material layer on the interdigitated electrode, and then vacuum dry. Step 3.7, drop the MXene dispersion onto the dielectric material layer, and use a spin coater to form a MXene wrinkle layer on the dielectric material layer. Step 3.8: Vacuum dry the substrate together to obtain the PVDF-TrFE-MXene sensing layer.

9. The method for preparing a rainfall monitoring sensor based on a MXene flexible composite material according to claim 5, characterized in that: The MXene etching solution is a mixed solution of LiF and hydrochloric acid.

10. The method for preparing a rainfall monitoring sensor based on a MXene flexible composite material according to claim 5, characterized in that: The concentration of MXene nanopowder in the monolayer MXene dispersion is 5 mg / ml.

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