Wearable sensor for detecting plant growth state

Abstract

The invention discloses a wearable sensor for detecting a plant growth state. The wearable sensor comprises a flexible substrate layer, a polyimide layer located on the flexible substrate layer, a flexible electrode layer and a transparent conductive layer which are located on the polyimide layer, a flexible sensing device layer located on the flexible electrode layer, and a nano-structure layer located on the transparent conductive layer, the flexible electrode layer is an annular electrode, and the transparent conductive layer and the nano-structure layer are located in the middle of the annular electrode; the sensor is attached to the surface of a plant through the viscosity of the flexible substrate layer of the wearable sensor, and due to the flexible wearable characteristic of the sensor, the sensor can adapt to various irregular surfaces of the plant and can be attached to the surface of a plant leaf without damaging the plant; the wearable sensor can realize long-time and non-destructive detection, and the detector surface Raman enhanced spectrum can realize non-destructive detection of the plant epidermis pesticide content and alkaloid, so as to judge whether the plant may suffer from diseases or not.

Description

Technical Field

[0001] The present invention relates to the field of flexible sensors, and in particular to a wearable sensor structure for detecting plant growth status and a preparation and use method thereof. Background Art

[0002] There are about 300,000 species of plants, accounting for more than 80% of the total amount of organisms on Earth. Plants are not only the source of food, medicine, industrial raw materials and energy, but also determine the environment and climate of the Earth. The growth state of plants directly reflects the health and survival ability of plants, and plays a decisive role in the health of plants. The growth state of plants is related to many factors, such as water, humidity, temperature, biological nutrition, pesticides, hormones in the body, etc. Water is an important component of plant protoplasm and a key factor for photosynthesis, nutrient transport and transpiration of plants. Water has a very significant impact on the growth state of plants. When the water loss of plants exceeds the water absorption, the water content of their tissues decreases, and they cannot carry out normal metabolism, the plants will have problems such as weakened photosynthesis, abnormal hormone content, and protoplasm damage of cells. The detection of plant moisture can not only ensure the growth state of plants, but also avoid the existing irrigation methods, realize precise irrigation of plants, and reduce the waste of water resources. Pesticides are crucial in the growth state of plants. They can effectively prevent, eliminate or control diseases, insects, weeds and other harmful organisms that endanger agriculture, protect the healthy growth of crops and improve the external and internal quality of crops. Testing plant pesticides can prevent some plants from being affected by lack of pesticides, while also reducing environmental pollution caused by excessive spraying of pesticides.

[0003] Traditional rigid sensors cannot be deformed, which makes it impossible to effectively adhere to the surface of plants. Long-term use of rigid sensors may have a certain impact on the growth of plants and may damage the plants themselves. Traditional plant pesticide or hormone testing requires manual sampling and advance sample processing, which may also damage the plants themselves. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a wearable sensor for detecting plant growth status. The sensor uses laser-induced graphene technology and graphene oxide as a moisture-sensitive material to realize in-situ, non-destructive and rapid detection of plant moisture, so as to provide timely warning of plant water shortage and drought. The sensor structure design amplifies the detection signal, and surface Raman enhanced spectroscopy is used to realize non-destructive detection of pesticide content and alkaloids in plant epidermis.

[0005] To achieve the above objectives, the technical solution of the present invention is: A wearable sensor for detecting plant growth status includes a flexible substrate layer, and is characterized in that it also includes a polyimide layer located on the flexible substrate layer, a flexible electrode layer and a transparent conductive layer located on the polyimide layer, a flexible sensing device layer located on the flexible electrode layer, and a nanostructure layer located on the transparent conductive layer; the flexible electrode layer is a ring electrode, and the transparent conductive layer and the nanostructure layer are located in the middle of the ring electrode.

[0006] Furthermore, the flexible substrate layer may include, but is not limited to, one or more of polyimide, polydimethylsiloxane, polyethylene terephthalate, polyester resin and ultra-thin adhesive tape.

[0007] Furthermore, the transparent conductive layer and the nanostructure layer are placed in the middle of the annular electrode as surface Raman enhanced spectroscopy substrates.

[0008] Furthermore, the flexible electrode layer is a cross-electrode structure.

[0009] Furthermore, the transparent conductive layer includes but is not limited to one or more of indium tin oxide, graphene, carbon nanowires, and metal nanowires.

[0010] A method for preparing a wearable sensor for detecting plant growth status, the method comprising the following steps: Step 1: evenly apply the polydimethylsiloxane (PDMS) mixed solution to the acrylic template and heat and cure it to obtain a flexible substrate layer.

[0011] Step 2: Evenly attach the polyimide to the cured polydimethylsiloxane to obtain a polyimide layer.

[0012] Step 3: Use laser induced graphene technology to prepare cross electrodes on polyimide as a flexible electrode layer.

[0013] Step 4: Drop-coat graphene oxide on the cross-electrodes in step 3 as a flexible sensing device layer.

[0014] Step 5: Evaporate indium tin oxide on the polyimide as a circular transparent conductive layer.

[0015] Step 6: Evenly apply the nanoparticle solution on the surface of the transparent conductive layer, and obtain a circular nanostructure layer after vacuum drying.

[0016] Furthermore, in the step 1, the PDMS mixed solution is a mixture of polydimethylsiloxane solution and curing agent in a ratio of 10:1; the curing temperature is 60° C., and the curing time is 1 hour.

[0017] Furthermore, the preparation method of the flexible electrode layer 3 in step three includes drawing a cross-electrode image using CAD, importing the engraving software LightBurn, and using an engraving machine to laser-induce graphene with an engraving speed of 2300 mm / s, a maximum power of 22.5%, and a cycle number of 1.

[0018] Furthermore, the step five includes evaporating 200 nm of indium tin oxide on the polyimide as a transparent conductive layer.

[0019] A method for detecting plant growth status using the wearable sensor for detecting plant growth status, the method comprising: Adhering the wearable sensor to the plant surface by using the adhesiveness of the flexible base layer of the wearable sensor; Connecting the electrode pins of the flexible ring-shaped cross electrode of the wearable sensor through an LCR meter, reading the capacitance reading of the LCR meter to obtain the capacitance value, each of which has a corresponding plant water content; The plant attached to the sensor is placed under a Raman spectrometer, and the microscope of the Raman spectrometer is used to focus on the Raman substrate of the sensor to obtain the Raman spectrum signal; Each Raman spectral signal feature corresponds to a compound, and the compound contained in the plant is determined based on the obtained Raman spectral signal features.

[0020] The beneficial effects of the present invention are: 1. Traditional rigid sensors cannot be effectively attached to the surface of plants because they cannot be deformed. Long-term use of rigid sensors may have a certain impact on the growth of the plants themselves and may damage the plants themselves. The present invention attaches the wearable sensor to the surface of the plant through the viscosity of the flexible base layer of the wearable sensor. Due to the flexible and wearable characteristics of the sensor of the present invention, it can adapt to various irregular surfaces of plants and can be attached to leaves, fruits and vegetables without damaging the plants themselves. The wearable sensor of the present invention has excellent flexibility, ductility and biocompatibility, and can achieve in-situ, long-term and non-destructive detection.

[0021] 2. The wearable sensor prepared by the present invention can realize rapid and stable moisture detection on the plant surface, and can accurately measure the water content of the plant. Therefore, the growth status of the plant can be evaluated by the detection results and, to a certain extent, early warning can be given to the water shortage and drought of the plant, thereby realizing the detection of the growth status of the plant.

[0022] 3. Traditional plant pesticide or hormone detection requires manual sampling, advance sample processing, and may damage the plant itself. The present invention uses the detector surface Raman enhanced spectroscopy to achieve non-destructive detection of plant epidermal pesticide content and alkaloids. The present invention uses a transparent conductive layer and a nanostructure layer as a surface Raman enhanced spectroscopy substrate on a wearable sensor, and determines what type of compound it belongs to by the collected Raman spectral signal characteristics.

[0023] 4. Compared with ordinary spectral detection, the method of the present invention can utilize the nanostructure layer to amplify the spectral signal, greatly improving the detection sensitivity; it can realize the detection of the amount of pesticide residues in plants, thereby determining whether the plants may suffer from diseases.

[0024] 5. The present invention has the advantages of low production cost and simple production method, and can be subsequently applied to smart agriculture to realize unmanned and intelligent monitoring of plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a wearable sensor for detecting plant growth status according to the present invention.

[0026] Figure 2 Schematic diagram of the flexible electrode of the present invention.

[0027] Figure 3 The relationship between the capacitance value and humidity of sensors with different spacing.

[0028] Figure 4 This is the sensitivity response diagram of the sensor under different humidity environments of the present invention.

[0029] Figure 5 It is the dynamic sensitivity response diagram of the transfer sensor under different humidity of the present invention.

[0030] Figure 6 This is the enhancement effect of the SERS substrate under different film pressure values.

[0031] Figure 7 This is the Raman spectrum of thiram detected by the present invention.

[0032] In the figure: 1. Flexible substrate layer; 2. Polyimide layer; 3. Flexible electrode layer; 4. Flexible sensing device layer; 5. Transparent conductive layer; 6. Nanostructure layer. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the invention clearer, the present invention is further described below with reference to the accompanying drawings.

[0034] like Figure 1As shown, a wearable sensor for detecting plant growth status of the present invention includes a flexible substrate layer 1, a polyimide layer 2, a flexible electrode layer 3, a flexible sensing device layer 4, a transparent conductive layer 5 and a nanostructure layer 6.

[0035] The flexible substrate layer 1 may include but is not limited to one or more of polyimide, polydimethylsiloxane, polyethylene terephthalate, polyester resin and ultra-thin adhesive tape.

[0036] The thickness of the polyimide layer 2 can be selected to be 35 μm, 80 μm, 100 μm, 230 μm, etc. The power and speed of the graphene induced by polyimide of different thicknesses are different.

[0037] The flexible electrode layer 3 can be prepared by transfer printing, screen printing, inkjet printing, laser cutting, laser direct writing, photolithography, etc. Figure 2 As shown, the flexible electrode layer 1 adopts a cross electrode structure, and parallel cross electrodes and annular electrodes can be selected.

[0038] The flexible sensing device layer 4 is used to detect the water vapor released by plant transpiration to measure the water content of plant leaves. When the water content of the plant is sufficient, the transpiration will be strengthened; when the water content of the plant is insufficient, the transpiration will be weakened. The measurement principle is that graphene oxide, as a nanomaterial with a large specific surface area, has an affinity for water molecules. When plants undergo transpiration, water molecules are released. After graphene oxide adsorbs these water molecules, the graphene oxide functional groups can form hydrogen bonds with water molecules, thereby affecting the conductivity, so that the water content of the plant can be expressed through changes in capacitance. Furthermore, the flexible sensing device layer 4 can be selected from graphene or graphene oxide.

[0039] The nanostructure layer 6 excites corresponding resonance peaks through the plasma resonance effect, thereby enhancing the interaction between the spectrum and matter, and further improving the detection sensitivity of the spectrum.

[0040] The material of the transparent conductive layer 5 includes but is not limited to indium tin oxide, graphene, carbon nanowires, metal nanowires, etc.

[0041] In the plant wearable sensor provided by the present invention, the flexible electrode layer 3 adopts a ring electrode, and the transparent conductive layer 5 and the nanostructure layer 6 are placed in the middle of the ring as a surface Raman enhanced spectroscopy substrate. The surface Raman enhanced spectroscopy substrate can absorb more charged ions and improve the detection accuracy of the sensor.

[0042] The present invention provides a method for preparing a wearable sensor for detecting plant growth status, comprising the following steps: Step 1: evenly apply the polydimethylsiloxane (PDMS) mixed solution to a homemade acrylic template and heat and cure it to obtain a flexible substrate layer 1.

[0043] Step 2: evenly attaching polyimide to the cured polydimethylsiloxane to obtain a polyimide layer 2.

[0044] Step 3: Using laser induced graphene technology to prepare cross electrodes on polyimide as a flexible electrode layer 3. Figure 3 As shown, sensors with spacings of 0.3mm, 0.45mm, and 0.6mm were prepared experimentally. It can be seen from the figure that as the spacing decreases, the capacitance value increases, indicating that the sensitivity of the sensor is better.

[0045] Step 4: drop-coat graphene oxide on the cross-electrodes of step 3 as the flexible sensing device layer 4.

[0046] Step 5: Vapor-deposit indium tin oxide on the polyimide to form a circular transparent conductive layer 5.

[0047] Step 6: Transfer the nanoparticle solution to the surface of the transparent conductive layer, and obtain a circular nanostructure layer 6 after vacuum drying. The nanoparticles are obtained by a self-assembly method, the nanoparticle material is silver, and the optimal size is 45nm. The process of transferring the nanoparticles to the transparent conductive layer 5 is completed by using a syringe and an LB film instrument, and the syringe injection rate is 0.4mL / min, and the optimal film pressure value is 55 mN / m.

[0048] In the step 1, the PDMS mixed solution is a mixture of polydimethylsiloxane solution and a curing agent in a ratio of 10:1; the curing temperature is 60° C., the curing time is 1 hour, and the curing agent can be tetramethylcyclotetrasiloxane.

[0049] The cured PDMS mixed solution has a certain degree of viscosity. In the step 2, a thinner polyimide plate can be attached to the cured polydimethylsiloxane. If it is a thicker polyimide plate, an adhesive tape can be set to attach the polyimide plate to the cured polydimethylsiloxane.

[0050] In step 3, the required cross electrode image is drawn using CAD, imported into the engraving software LightBurn, and the graphene is laser-induced using the L6 engraving machine. The engraving speed is 2300 mm / min, the maximum power is 22.5%, and the number of cycles is 1. Figure 3 As shown, according to the preparation method, the spacing between adjacent cross electrodes prepared in the experiment is 0.3mm, 0.45mm or 0.6mm, and the response curve of the cross electrode test sensor to humidity is prepared. It can be seen from the figure that as the spacing decreases, the larger the capacitance value, the better the sensitivity of the sensor, and the cross electrodes with a spacing of 0.3mm have the greatest sensitivity to humidity response.

[0051] In step 4, 1 mL of 0.5 mg / mL graphene oxide is the optimal solution volume and content.

[0052] The method for manufacturing the transparent conductive layer in step five includes, but is not limited to, sputtering deposition, evaporation, deposition, spin coating, and spraying. The nanoparticle solution in step 6 is obtained by self-assembly. The nanoparticles can be made of silver or gold and have a size of 10-80 nm. The process of transferring the nanoparticles to the transparent conductive layer 5 is completed by using a syringe and an LB film instrument. The syringe injection rate is 0.4 mL / min and the optimal film pressure is 55 mN / m. The optimal film pressure is performed using crystal violet (CV) because the Raman scattering area of ​​crystal violet is large. Figure 6 As shown in the figure, the experiment used crystal violet (CV) as a probe molecule for detecting the Raman substrate enhancement effect, and prepared SERS substrates of 40 mN / m, 45 mN / m, 50 mN / m, 55 mN / m, and 58 mN / m. From the experimental structure, when the membrane pressure increased from 40 mN / m to 55 mN / m, the Raman spectrum signal gradually increased. This is because the larger the membrane pressure value, the smaller the gap between the nanoparticles, which is more conducive to the generation of plasma resonance. However, when the membrane pressure exceeds 55mN / m, the structure is destroyed and the Raman intensity decreases. Therefore, the optimal membrane pressure value is 55mN / m. Among them, the Raman shift (cm -1 ), Raman intensity (cps).

[0053] The present invention provides a method for detecting the growth status of plants: based on the above-made sensor, the sensor is attached to the surface of plant leaves, the capacitance value of the sensor is measured by an LCR meter, and the Raman spectrum signal is collected by a Raman spectrometer. A model is established with the collected capacitance value, and the relationship between the water content of the plant and the transpiration of the plant is compared and analyzed, so as to judge the water status of the plant.

[0054] To collect plant water content information, the wearable sensor can be attached to plant leaves, such as Figure 4 and Figure 5 As shown, an oscillation circuit is used to collect the capacitance changes of the sensor caused by the influence of moisture. These capacitance changes will be configured in the signal acquisition module through the I / O port connected to the controller, and a communication protocol is written to read the required data, and the capacitance changes are converted into digital signals. The control module operates on the digital signals and finally outputs the moisture content information to the display device to display the moisture content.

[0055] Figure 4 and Figure 5In the table, RH is relative humidity, which refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the current temperature. It reflects the degree of air distance from saturated air and represents the ratio of the absolute humidity in the air to the saturated absolute humidity at the same temperature and pressure. It is a percentage value, that is, the ratio of the mass of water vapor contained in a certain humid air to the mass of water vapor contained in saturated air at the same temperature and pressure.

[0056] Figure 4 The capacitance change characteristics of the sensor in different relative humidity environments. Specifically, when the sensor is transferred from a 22% relative humidity environment to a 94.3% relative humidity environment, its capacitance value increases significantly, showing excellent humidity responsiveness. Under low humidity (22% RH) conditions, the capacitance value of the sensor remains at a low level of about 90PF, while under high humidity (94.3% RH) conditions, the capacitance value increases rapidly to about 100,000PF and remains stable for about 100 seconds to 400 seconds.

[0057] Figure 5 and Figure 3 Similarly, when the sensor moves from a high humidity condition to a low humidity environment, its capacitance value changes gradually.

[0058] Figure 4 and 5 The high sensitivity of the sensor to humidity changes and its fast response time are clearly demonstrated, thus verifying the effectiveness and reliability of the sensor in humidity monitoring applications.

[0059] In the present invention, the relationship between the capacitance value and the plant moisture content is usually determined in advance, the capacitance value of the sensor is measured by an LCR meter, and the plant moisture content corresponding to the capacitance value is measured by a humidity sensor to obtain multiple capacitance values ​​and the plant moisture content corresponding to the capacitance values. The multiple capacitance values ​​and the plant moisture content corresponding to the capacitance values ​​are stored in a computer as a database. In subsequent experiments, the humidity sensor is no longer required. After the capacitance value of the sensor is measured by the LCR meter, the plant moisture content corresponding to the capacitance value can be output from the database, thereby achieving continuous detection of plants through the sensor of the present invention.

[0060] In the present invention, the collected Raman spectrum signal is smoothed, denoised and baseline corrected, and then the spectrum signal is intercepted to a suitable band for feature extraction, and the extracted characteristic peak information is compared with the existing spectrum library of the sample to be detected.

[0061] The Raman spectrum described above is a scattering spectrum, which is an inelastic scattering phenomenon that occurs when light interacts with matter. Raman spectrum is called a "fingerprint spectrum" because each molecule has its own unique Raman spectrum. In the Raman spectrum, each Raman peak represents the wavelength position and intensity of the corresponding Raman scattered light. Each spectrum peak corresponds to a specific molecular bond vibration. The type of molecules that make up the substance can be identified according to this principle. After obtaining the characteristic peak of the Raman signal, since each compound has a corresponding characteristic peak of the Raman signal, it can be determined what kind of compound it belongs to based on the obtained characteristic peak of the Raman signal.

[0062] According to the method for detecting the plant growth status provided by the present invention, the detection target compounds include: thiram, zineb, mancozeb, ethanol, nicotine and the like. Example

[0063] The present invention provides a plant wearable sensor, and the specific manufacturing process includes the following steps: 1. Production of flexible substrate layer; The polydimethylsiloxane solution and the curing agent were mixed in a ratio of 10:1, and the mixed solution was stirred evenly with a glass rod until dense and uniform bubbles appeared, and then the solution was placed in a vacuum pump and evacuated until no bubbles emerged. The mixed solution was coated on a homemade acrylic plate, and the coated acrylic plate was placed in a 60°C oven for 1 hour, and the cured polydimethylsiloxane was taken out as a flexible substrate layer.

[0064] 2. Preparation of flexible electrodes; The polyimide is flatly attached to the cured polydimethylsiloxane, the required pattern is imported into the laser engraving software, and then the L6 engraving machine is used, the focal length is set to 5mm, the laser power is 22.5%, and the engraving speed is 2300mm / min. Then the polyimide absorbs the incident photon energy and converts it into heat energy to destroy the CN and CO chemical bonds in the polyimide. The polyimide is finally decomposed by heat and carbonized, and the gas is quickly released to produce graphene. At the same time, the patterning of graphene is also completed in the process of using laser-induced graphene, and a flexible electrode based on laser-induced graphene is obtained.

[0065] 3. Preparation of flexible sensing devices; Take graphene oxide with a concentration of 0.5 mg / mL, place it in a water bath ultrasonic machine and run it at a power of 100 W for 5 minutes, then evenly drop the graphene oxide evenly dispersed after ultrasound on the working area of ​​the laser-induced graphene flexible electrode, place it on the workbench and let it stand. After natural drying, a graphene oxide film is obtained as a flexible sensing device.

[0066] 4. Preparation of transparent conductive layer; 200 nm of indium tin oxide was evaporated on the polyimide as a transparent conductive layer.

[0067] 5. Fabrication of nanostructured layer; First, 45 nm silver nanoparticles were synthesized: 0.1 mg / mL PEG-SH chloroform solution was prepared; the silver nanoparticle solution, PEG-SH chloroform solution, and methanol solution were fully mixed at a volume ratio of 1:1:1. The mixture was centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was redissolved to one-third of the original volume with chloroform solution; centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was redissolved to one-third of the original volume with chloroform solution; centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was redissolved to one-tenth of the original volume with chloroform solution; then the concentration of silver nanoparticles was increased by centrifugation, and these high-concentration silver nanoparticle solutions were transferred to the surface of the transparent conductive layer using a syringe and the water surface tension was monitored using an LB film analyzer (by Figure 6 By comparison, the optimal tension is 55mN / m), and the nano-silver cubes are uniformly and completely transferred to the surface of the transparent conductive layer as a dense single molecular layer. Finally, they are dried in a vacuum drying oven at room temperature, so that the silver nano-particle cube layer forms a nano-structure layer on the surface of the transparent conductive layer. The nano-structure layer is the core of the sensor and is used to amplify the Raman signal.

[0068] Flexible electrodes such as Figure 2 As shown, the rings are crossed electrodes and the circle in the middle is the Raman substrate. Example

[0069] According to the plant wearable sensor provided by the present invention, the method for detecting the growth status of a plant includes: 1. Using the stickiness of the flexible substrate layer of the wearable sensor, the sensors prepared above were attached to the surfaces of different samples, and watering and water-free treatments were performed, and pesticides were dripped on the samples; 2. After a predetermined time, connect the electrode pins of the flexible ring cross electrode through the LCR meter and read the LCR meter capacitance reading. Perform multiple measurements to establish a model of the relationship between capacitance value and plant water status.

[0070] 3. Place the sample attached to the sensor under the Raman spectrometer, use the microscope of the Raman spectrometer to focus on the Raman substrate of the sensor, adjust the laser wavelength to 785nm (or 514nm, 532nm, 633nm, 780nm, 830nm), and adjust the laser energy and aperture to obtain a clear Raman spectrum signal.

[0071] 4. Sampling can be repeated multiple times according to the set sampling points of the Raman substrate.

[0072] 5. Intercept the appropriate wavelength of the collected Raman signal and save the data in the computer; use Python / Matable software to train the model in the computer, eliminate the interference of the original data, and extract the characteristic peak information of the Raman signal.

[0073] 6. Compare with the Raman spectrum library of the sample to be tested, the collected Raman spectrum signal is the characteristic peak information of the target compound.

[0074] Raman spectroscopy is a technique commonly used to analyze molecular structural characteristics because its unique spectral lines can be used as a "fingerprint" to identify molecules. The characteristic peaks in this spectrum can reveal the bond types in chemical molecules. However, the signal of Raman spectroscopy is very weak, and metal nanostructures (such as gold and silver) are required to enhance the signal. The enhancement principle is that when light shines on the surface of metal nanostructures such as gold and silver, it will induce surface plasma resonance. This phenomenon will generate a strong local electromagnetic field, which will significantly amplify the Raman scattering signals of molecules close to these metal nanostructures. This signal amplification greatly improves the sensitivity and selectivity of detection.

[0075] The samples of the present invention may be plant leaves, crops, fruits and vegetables.

[0076] According to the method for detecting the growth status of a plant provided by the present invention, the target compounds detected by surface Raman enhanced spectroscopy can be: thiram, zineb, mancozeb, ethanol, nicotine and the like. Example

[0077] Taking the plant wearable sensor made by the present invention to detect thiram as an example, the specific measurement process includes the following: S1. Sample preparation: Tomato leaves are selected as samples. Tomatoes should be selected at a specific developmental stage to avoid experimental instability and ensure the presence of the markers to be tested. The sensor is attached to the surface of the tomato leaf.

[0078] S2. Drip coating of the sample to be tested: Take 5L of thiram solution and drip it on the sensor Raman substrate (combination of 5 and 6). Repeat three times to obtain three reference sample points.

[0079] S3. Raman spectrum signal acquisition: Place the sample in a Raman spectrometer with a laser wavelength of 758nm, a laser energy of 2mv, and an aperture of 50um; Aim the laser beam at the sensor Raman substrate to collect spectrum data.

[0080] S4. Data processing: The collected Raman data contains interference information such as background, noise, power fluctuation, etc. Therefore, it is necessary to perform normalization, calibration, denoising, baseline correction, smoothing and other processing to optimize the spectral data.

[0081] S5. Feature extraction: Analyze the processed spectral data, extract the required bands, and find the characteristic peaks related to thiram.

[0082] S6. Data comparison: Compare the obtained characteristic peak information with the existing known spectrum information of thiram to determine the accuracy of the detection.

[0083] Thiram test results Figure 7 shown.

[0084] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

Claims

1. A wearable sensor for detecting plant growth status, comprising a flexible substrate layer (1), characterized in that: It also comprises a polyimide layer (2) located on the flexible substrate layer (1), a flexible electrode layer (3) and a transparent conductive layer (5) located on the polyimide (2), a flexible sensing device layer (4) located on the flexible electrode layer (3), and a nanostructure layer (6) located on the transparent conductive layer (5); the flexible electrode layer (3) is a ring electrode, and the transparent conductive layer (5) and the nanostructure layer (6) are located in the middle of the ring electrode.

2. A wearable sensor for detecting plant growth status according to claim 1, characterized in that: The flexible substrate layer (1) is polydimethylsiloxane.

3. A wearable sensor for detecting plant growth status according to claim 1, characterized in that: The transparent conductive layer (5) and the nanostructure layer (6) serve as surface Raman enhanced spectroscopy substrates and are placed in the middle of the annular electrode.

4. A wearable sensor for detecting plant growth status according to claim 1, characterized in that: The flexible electrode layer (3) is a cross-electrode structure, and the transparent conductive layer (5) is indium tin oxide.

5. A method for preparing a wearable sensor for detecting plant growth status according to claim 1, characterized in that: The method comprises the following steps: Step 1: Spin-coat a polydimethylsiloxane (PDMS) mixed solution onto an acrylic template and heat and solidify the resultant flexible substrate layer (1); Step 2: attaching polyimide to the cured polydimethylsiloxane to obtain a polyimide layer (2); Step 3: Using laser induced graphene technology to prepare cross electrodes on polyimide as a flexible electrode layer (3); Step 4: drop-coating graphene oxide on the cross-electrodes in step 3 as a flexible sensing device layer (4); Step 5: sputtering indium tin oxide on the polyimide as a circular transparent conductive layer (5); Step 6: Transfer the nanoparticle solution to the surface of the transparent conductive layer (5), and obtain a circular nanostructure layer (6) after vacuum drying.

6. The method for preparing a wearable sensor for detecting plant growth status according to claim 5, characterized in that: In the step 1, the PDMS mixed solution is spin-coated at a speed of 3000 rpm, a spin-coating time of 60 s, and a spin-coating thickness of 80 um; the curing temperature is 60° C., and the curing time is 1 h.

7. The method for preparing a wearable sensor for detecting plant growth status according to claim 5, characterized in that: The method for preparing the flexible electrode layer (3) in step 3 comprises drawing a cross electrode image using CAD, importing the image into engraving software LightBurn, and using an engraving machine to induce graphene by laser, with an engraving speed of 2300 mm / min, a maximum power of 22.5%, and a cycle number of 1. The spacing between adjacent cross electrodes prepared is 0.3 mm, 0.45 mm, or 0.6 mm.

8. The method for preparing a wearable sensor for detecting plant growth status according to claim 5, characterized in that: The step five includes sputtering 200 nm of indium tin oxide on the polyimide as a transparent conductive layer (5).

9. The method for preparing a wearable sensor for detecting plant growth status according to claim 5, characterized in that: In step six, the nanoparticles are made of silver and have a size of 45 nm. The nanoparticles are transferred to the transparent conductive layer (5) by using a syringe. The injection rate of the syringe is 0.4 mL / min and the membrane pressure value is 55 mN / m.

10. A method for detecting plant growth status using the wearable sensor for detecting plant growth status according to claim 1, characterized in that: The method comprises: Adhering the wearable sensor to the plant surface by using the adhesiveness of the flexible base layer of the wearable sensor; Connecting the electrode pins of the flexible ring-shaped cross electrode of the wearable sensor through an LCR meter, reading the capacitance reading of the LCR meter to obtain the capacitance value, each of which has a corresponding plant water content; The plant attached to the sensor is placed under a Raman spectrometer, and the microscope of the Raman spectrometer is used to focus on the Raman substrate of the sensor to obtain the Raman spectrum signal; Each Raman spectral signal feature corresponds to a compound, and the compound contained in the plant is determined based on the obtained Raman spectral signal features.

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