Flexible sensor for plant detection and manufacturing method

Abstract

The invention relates to the technical field of plant detection, and discloses a flexible sensor for plant detection and a manufacturing method.The flexible sensor comprises an upper substrate, a lower substrate and a clamping substrate, a moisture detection layer is arranged on the upper surface of the upper substrate, a groove is formed in the moisture detection layer, and liquid metal is injected into the groove; a moisture detection layer is arranged on the upper surface of the lower substrate, a VOCs detection layer is arranged on the upper surface of the moisture detection layer, a sensitive film is arranged on the VOCs detection layer, a humidity detection layer is arranged on the lower surface of the lower substrate, and an interdigital electrode is arranged on the humidity detection layer; during use, by arranging the moisture detection layer, the VOCs detection layer and the humidity detection layer, moisture, VOCs and humidity detection can be achieved through one sensor, and multi-parameter integrated detection is achieved.

Description

Technical Field

[0001] This invention relates to the field of plant detection technology, specifically to a flexible sensor for plant detection and its manufacturing method. Background Technology

[0002] As the main organs for photosynthesis and transpiration in plants, leaves are key indicators reflecting crop water status, nutritional health, and stress response. Precise, in-situ, and continuous monitoring of leaf physiological parameters is a core technological prerequisite for achieving precision irrigation, early disease warning, and crop physiological research in smart agriculture.

[0003] Currently, plant leaf testing is mostly conducted through the following two methods: 1. Detection is carried out using rigid detection equipment such as time domain reflectometers (TDR) and chlorophyll fluorometers. However, this method usually requires destructive sampling or cannot achieve in-situ continuous monitoring. Furthermore, the rigid structure of these devices can create a mechanical mismatch with the soft plant leaves, potentially compressing leaf veins during attachment, affecting normal leaf growth and photosynthesis, and even inducing stress responses in the plant, leading to distorted monitoring data. In addition, these devices generally suffer from large size, high power consumption, high cost, and lack of wireless data transmission capabilities, making large-scale distributed deployment in the field difficult. Second: Detection using flexible sensors. Although the development of flexible electronics technology has made it possible to solve the interface adhesion problem of rigid detection equipment, existing flexible sensors used for plant leaf detection still have the following shortcomings: Firstly, there is a problem with interface stability. Flexible sensors rely on tape or adhesive hydrogel for fixation, which makes it difficult to adapt to the dynamic growth of leaves (such as extension and curling) and disturbances in the field environment (such as wind). They are prone to falling off or creating contact gaps, resulting in unstable signals or failure. Secondly, the anti-interference ability is poor. Temperature fluctuations can cause the electrical properties of the sensor's sensitive materials to drift, resulting in errors in the monitoring signal. Especially in environments with large temperature differences (such as greenhouses and arid regions), the temperature error generally exceeds ±5.2%, which seriously affects the reliability of the data. Finally, the functional integration is low. Most flexible sensors can only monitor a single parameter (such as humidity or temperature) and cannot simultaneously acquire multi-dimensional related information such as "moisture-transpiration-VOCs-microclimate". They also cannot perform wireless communication, making it difficult to support comprehensive diagnosis and early warning of crop stress states such as drought and disease, as well as real-time data uploading. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a flexible sensor for plant detection and a method for manufacturing it. All the technical problems solved are that existing flexible sensors for plant detection have poor interface stability, low functional integration and cannot detect multiple parameters.

[0005] To solve the above technical problems, in a first aspect, the present invention provides the following technical solution: a flexible sensor for plant detection, comprising an upper base, a lower base, and a clamping base, wherein the clamping base is connected to the same side of the upper base and the lower base, respectively; A moisture detection layer is provided on the upper surface of the upper substrate. A groove is formed on the moisture detection layer. Liquid metal is injected into the groove. The injected liquid metal is a varistor. A first resistor is also provided on the moisture detection layer. The first resistor is connected in series with the varistor to form a voltage divider branch. A VOCs detection layer is provided on the upper surface of the moisture detection layer, and a sensitive film is provided on the VOCs detection layer. The sensitive film is a reduced graphene oxide film or a silver nanowire composite film. A humidity detection layer is provided on the lower surface of the lower substrate, an interdigitated electrode is provided on the humidity detection layer, a PDMS dielectric layer is provided on the surface of the interdigitated electrode, and a second resistor is provided on the humidity detection layer. The second resistor is electrically connected to the interdigitated electrode to form an RC oscillator. The clamping base is respectively provided with an MCU control unit, a wireless communication unit and a power supply unit. The power supply unit is used to provide operating voltage for the MCU control unit, the wireless communication unit and the voltage divider branch. One end of the varistor, which is electrically connected to the first resistor, is electrically connected to the analog-to-digital conversion input terminal of the MCU control unit. The MCU control unit is used to perform analog-to-digital conversion on the voltage of the varistor, calculate the resistance value of the varistor based on the voltage on the varistor, the operating voltage, and the resistance value of the first resistor, and obtain the moisture detection value based on the resistance value of the varistor. The current output terminal of the MCU main control unit is connected to the sensitive film to input a constant current to the sensitive film. The analog-to-digital conversion input terminal of the MCU main control unit is also electrically connected to the sensitive film to obtain the voltage of the sensitive film and obtain the VOCs detection value based on the voltage of the sensitive film. The interrupt input terminal of the MCU main control unit is electrically connected to the output terminal of the RC oscillator, which is used to detect the oscillation frequency of the RC oscillator, obtain the capacitance value of the interdigitated electrode through the oscillation frequency of the RC oscillator, and obtain the humidity detection value based on the capacitance value of the differential interdigitated electrode. The MCU main control unit is electrically connected to the wireless communication unit, and sends the moisture detection value, VOCs detection value and humidity detection value to the remote terminal through the wireless communication unit.

[0006] In one embodiment of the first aspect, the upper substrate, the lower substrate, and the clamping substrate are prepared by mixing hydroxyl-modified polydimethylsiloxane, a silane coupling agent, and a self-healing accelerator in a ratio of 100:5:3. The sensitive film has a paper-cut structure shape.

[0007] In one embodiment of the first aspect, the groove includes a main groove and branch grooves, the distribution of which on the moisture detection layer matches the leaf veins.

[0008] In one embodiment of the first aspect, the porosity of the PDMS dielectric layer is between 45% ± 3%, the pore size is between 1 and 5 μm, and the thickness is between 30 and 50 μm.

[0009] In one embodiment of the first aspect, protective layers are respectively provided on the upper surface of the VOCs detection layer, the lower surface of the humidity detection layer, and the clamping substrate.

[0010] In one embodiment of the first aspect, the protective layer comprises a poly(p-dichlorotoluene) layer and a transparent PDMS film disposed sequentially from the inside out.

[0011] In one embodiment of the first aspect, the water contact angle of the protective layer is greater than 110°, the thickness of the poly(p-dichlorotoluene) layer is between 150-200 nm, and the thickness of the transparent PDMS film is between 10-30 μm.

[0012] In one embodiment of the first aspect, the power supply unit includes a battery.

[0013] In one embodiment of the first aspect, the power supply unit further includes a photovoltaic panel and a charge / discharge management unit, the charge / discharge management unit being used to convert the output voltage of the photovoltaic panel into the charging voltage of the battery.

[0014] Secondly, the present invention also provides a method for manufacturing a flexible sensor for plant detection, comprising the following steps: S1: Fabricate the upper substrate, lower base, and clamping substrate, wherein the clamping substrate is connected to the same side of the upper substrate and the lower substrate, respectively. Specifically, first, mix hydroxyl-modified polydimethylsiloxane, silane coupling agent, and self-healing accelerator in a ratio of 100:5:3 to obtain a mixture; then, place the mixture into the mold corresponding to the upper substrate, lower base, and clamping substrate; then, cure the mold in an environment of 60°C for two hours; finally, demold. S2: A moisture detection layer is fabricated on the upper surface of the substrate. Then, a groove is fabricated on the moisture detection layer using a 1064nm laser. Next, liquid metal is injected into the groove at a pressure of 0.1MPa using a micro-injection pump to form a varistor. Finally, a first resistor is fabricated on the moisture detection layer and connected in series with the varistor. S3: A VOCs detection layer is fabricated on the upper surface of the moisture detection layer, and then a sensitive film is fabricated on the VOCs detection layer by CVD process. The sensitive film is a reduced graphene oxide film or a silver nanowire composite film. Then, the sensitive film is defined into a paper-cut structure shape by photolithography process. S4: A humidity detection layer is fabricated on the lower surface of the substrate. Then, interdigitated electrodes are fabricated on the humidity detection layer by magnetron sputtering. A PDMS dielectric layer is fabricated on the interdigitated electrodes by spin coating. The PDMS dielectric layer is then cured at 80°C. Finally, a second resistor is fabricated on the humidity detection layer, and the second resistor and the interdigitated electrodes form an RC oscillator. S5: Integrate the MCU control unit, wireless communication unit, and power supply unit on the clamping substrate, and electrically connect the varistor, RC oscillator, and sensitive film to the MCU main control unit; S6: Protective layers are respectively provided on the upper surface of the VOCs detection layer, the lower surface of the humidity detection layer, and the clamping substrate; the water contact angle of the protective layer is greater than 110°, including a polydichlorotoluene layer and a light-transmitting PDMS film arranged sequentially from the inside to the outside, the thickness of the polydichlorotoluene layer is 200nm, and the thickness of the light-transmitting PDMS film is between 10-30um.

[0015] The beneficial effects of this invention compared to the prior art are: Firstly, by setting up a moisture detection layer, a VOCs detection layer, and a humidity detection layer, this invention enables the detection of moisture, VOCs, and humidity through a single sensor, achieving integrated detection of multiple parameters. Secondly, since the upper and lower bases are attached to the upper and lower surfaces of the leaf, this application prepares the upper base, lower base and clamping base by mixing hydroxyl-modified polydimethylsiloxane, silane coupling agent and self-healing accelerator in a ratio of 100:5:3, so that the upper base and lower base have good adhesion, that is, they can adhere well to the leaf surface, have good air permeability and self-healing properties, and can adapt to leaf growth. Finally, by configuring the MCU control unit and wireless communication unit, the detected parameters can be sent to the remote terminal, thus realizing remote data transmission. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the flexible sensor in Example 1; Figure 2 This is a schematic diagram of the groove structure on the moisture detection layer in Example 1; Figure 3 This is a schematic diagram of the structure of the interdigitated electrodes on the humidity detection layer in Example 1; Figure 4 This is a schematic diagram of the flexible sensor on both sides of the blade in Example 1. Detailed Implementation

[0017] The illustrative embodiments of this application include, but are not limited to, a flexible sensor for plant detection and a method for manufacturing it.

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0019] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items. Words such as “comprising” or “including” mean that the element or object preceding “comprising” or “including” covers the element or object listed following “comprising” or “including” and its equivalents, and does not exclude other elements or objects. Words such as “connected” or “linked” are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect.

[0020] Example 1 like Figure 1 As shown, this embodiment provides a flexible sensor for plant detection, including an upper base 10, a lower base 11 and a clamping base 12, wherein the clamping base 12 is connected to the same side of the upper base 10 and the lower base 11 respectively. A moisture detection layer 2 is provided on the upper surface of the upper substrate 10, such as... Figure 2 As shown, a groove 20 is provided on the moisture detection layer 2, and liquid metal is injected into the groove 20. The injected liquid metal is a varistor. A first resistor is also provided on the moisture detection layer 2. The first resistor is connected in series with the varistor to form a voltage divider branch. A VOCs detection layer 3 is provided on the upper surface of the moisture detection layer 2. VOCs is an abbreviation for Volatile Organic Compounds. A sensitive film is provided on the VOCs detection layer 3. The sensitive film is a reduced graphene oxide film or a silver nanowire composite film. A humidity detection layer 4 is provided on the lower surface of the lower substrate 11, such as Figure 3 As shown, the humidity detection layer 4 is provided with interdigitated electrodes 30, the surface of the interdigitated electrodes 30 is provided with a PDMS dielectric layer, the humidity detection layer 4 is provided with a second resistor, and the second resistor is electrically connected to the interdigitated electrodes to form an RC oscillator. The clamping base 12 is provided with an MCU control unit, a wireless communication unit and a power supply unit respectively. The power supply unit is used to provide working voltage for the MCU control unit, the wireless communication unit and the voltage divider branch. One end of the varistor that is electrically connected to the first resistor is electrically connected to the analog-to-digital conversion input terminal of the MCU control unit; the MCU control unit is used to perform analog-to-digital conversion on the voltage of the varistor, calculate the resistance value of the varistor based on the voltage on the varistor, the operating voltage and the resistance value of the first resistor, and obtain the moisture detection value based on the resistance value of the varistor; The current output terminal of the MCU main control unit is connected to the sensitive film to input a constant current to the sensitive film. The analog-to-digital conversion input terminal of the MCU main control unit is also electrically connected to the sensitive film to obtain the voltage of the sensitive film and obtain the VOCs detection value based on the voltage of the sensitive film. The interrupt input terminal of the MCU main control unit is electrically connected to the output terminal of the RC oscillator to detect the oscillation frequency of the RC oscillator, obtain the capacitance value of the interdigitated electrode through the oscillation frequency of the RC oscillator, and obtain the humidity detection value based on the capacitance value of the differential interdigitated electrode. The MCU main control unit is electrically connected to the wireless communication unit, which sends the moisture detection value, VOCs detection value and humidity detection value to the remote terminal through the wireless communication unit.

[0021] In this embodiment, the design concept of the present invention is as follows: When the moisture content of the leaf changes, the groove deforms, which in turn causes a change in the resistance of the liquid metal, i.e., the varistor. Therefore, the amount of moisture in the leaf can be determined by detecting the resistance of the varistor. In addition, the liquid metal is a gallium-indium alloy with a purity of not less than 99.99%. Furthermore, the correspondence between the leaf moisture content and the varistor can be obtained in advance before the actual test, and then the amount of moisture in the leaf can be determined based on this correspondence and the resistance of the varistor during the actual test. During humidity detection, the transpiration of the leaf surface changes the ambient humidity, which in turn causes a change in the dielectric constant of the PDMS dielectric layer, ultimately leading to a change in the capacitance of the interdigitated electrode 40, which in turn changes the output clock frequency of the RC oscillator. Based on this, detection can be achieved. In addition, the correspondence between the output clock frequency of the RC oscillator and the ambient humidity can be obtained in advance before the actual detection. During the actual detection, the humidity level can be determined based on this correspondence and the clock frequency of the RC oscillator. When VOCs are detected, characteristic VOC molecules released by plants (such as stress-related hexenol) are adsorbed onto the surface of the sensitive membrane. The hydrogen bonds or halogen bonds in the RGO form a combined force and exert an effect, causing a change in the conductivity of the sensitive membrane. Based on this, VOCs can be detected. In addition, the correspondence between the conductivity of the sensitive membrane and VOCs can be obtained in advance before actual detection. During actual detection, VOCs can be detected based on this correspondence and the conductivity of the sensitive membrane.

[0022] In practical implementation, the flexible sensor in this embodiment, by setting a moisture detection layer 2, a VOCs detection layer 3, and a humidity detection layer 4, can achieve the detection of moisture, VOCs, and humidity with a single sensor, realizing multi-parameter integrated detection; in addition, the connection diagram between the flexible sensor and the blade can be referred to Figure 4 .

[0023] Specifically, in this embodiment, the upper substrate 10, the lower substrate 11, and the clamping substrate 12 are prepared by mixing hydroxyl-modified polydimethylsiloxane, silane coupling agent, and self-healing accelerator in a ratio of 100:5:3.

[0024] In actual implementation, since the upper substrate 10 and the lower substrate 11 are attached to the upper and lower surfaces of the leaf, this application prepares the upper substrate 10, the lower substrate 11 and the clamping substrate 12 by mixing hydroxyl-modified polydimethylsiloxane, silane coupling agent and self-healing accelerator in a ratio of 100:5:3. This results in the upper substrate 10 and the lower substrate 11 having good adhesion, that is, good adhesion to the leaf surface, air permeability and self-healing properties, which can adapt to leaf growth.

[0025] In practical applications, after cutting a 1mm wide slit in the sensor, its mechanical strength recovers to 92.5% and its resistance value recovers to 95.2% within 24 hours, enabling normal parameter monitoring.

[0026] In addition, the materials of the moisture detection layer 2, VOCs detection layer 3 and humidity detection layer can be the same as the materials of the upper substrate 10, lower substrate 11 and clamping substrate 12.

[0027] Specifically, in this embodiment, the sensitive film has a paper-cut structure shape, which can improve the flexibility of the sensor.

[0028] Specifically, in this embodiment, the groove 20 includes a main groove and branch grooves, and the distribution positions of the main groove and branch grooves on the moisture detection layer 2 match the leaf veins; in addition, the width of the main groove can be between 200±5 μm, and the width of the branch groove can be between 50±3 μm.

[0029] In one implementation, the main groove and the branch groove may or may not be connected, depending on the actual needs.

[0030] Specifically, in this embodiment, the porosity of the PDMS dielectric layer is between 45% ± 3%, the pore size is between 1-5 μm, and the thickness is between 30-50 μm; thus, the flexible sensor in this embodiment can have a response time of less than 1 second and a sensitivity of -145.7Ω / % RH when performing humidity detection.

[0031] Specifically, in this embodiment, in Figure 1 In the middle, protective layers 5 are respectively provided on the upper surface of VOCs detection layer 3, the lower surface of humidity detection layer 4, and the clamping substrate 12.

[0032] Furthermore, in this embodiment, the water contact angle of the protective layer 5 is greater than 110°, which can effectively prevent rainwater and dew from entering. The protective layer 5 includes a polydichlorotoluene layer and a light-transmitting PDMS film arranged sequentially from the inside out. The thickness of the polydichlorotoluene layer is between 150-200 nm, and the thickness of the light-transmitting PDMS film is between 10-30 μm.

[0033] In actual implementation, the protective layer 5 in this embodiment maintains high light transmittance (>90%) and high air permeability (>85%) to ensure that it does not affect the photosynthesis and gas exchange of the leaves.

[0034] Specifically, in this embodiment, the power supply unit includes a battery.

[0035] Furthermore, in order to achieve continuous power supply from the battery, the power supply unit also includes a photovoltaic panel and a charge / discharge management unit, which is used to convert the output voltage of the photovoltaic panel into the charging voltage of the battery.

[0036] In this embodiment, the model of the MCU in the MCU control unit is selected according to the implementation requirements. It is necessary to ensure that the MCU has a constant current output interface, an analog-to-digital conversion interface, and an interrupt input interface. Additionally, the wireless communication unit can be a Bluetooth communication unit.

[0037] Example 2 This embodiment also provides a method for manufacturing a flexible sensor for plant detection, including the following steps: S1: Fabricate the upper substrate 10, lower substrate 11, and clamping substrate 12, wherein the clamping substrate 12 is connected to the upper substrate 10 and the lower substrate 11 on the same side, as follows: First, mix hydroxyl-modified polydimethylsiloxane, silane coupling agent, and self-healing accelerator in a ratio of 100:5:3 to obtain a mixture; then place the mixture into the mold corresponding to the upper substrate 10, lower substrate 11, and clamping substrate 12; then cure the mold in an environment of 60°C for two hours; finally, demold. In practical implementation, since the upper substrate 10 and the lower substrate 11 are attached to the upper and lower surfaces of the leaf, this application prepares the upper substrate 10, the lower substrate 11 and the clamping substrate 12 by mixing hydroxyl-modified polydimethylsiloxane, silane coupling agent and self-healing accelerator in a ratio of 100:5:3. This results in the upper substrate 10 and the lower substrate 11 having good adhesion, that is, good adhesion to the leaf surface, air permeability and self-healing properties, which can adapt to leaf growth.

[0038] S2: A moisture detection layer 2 is fabricated on the upper surface of the upper substrate 10. Then, a groove 20 is fabricated on the moisture detection layer 2 using a 1064nm laser. Next, liquid metal is injected into the groove 20 under a pressure of 0.1MPa using a micro-injection pump to form a piezoresistor. Finally, a first resistor is fabricated on the moisture detection layer and connected in series with the piezoresistor. In addition, the liquid metal is a gallium-indium alloy with a purity of not less than 99.99%. Additionally, the groove 20 includes a main groove and branch grooves, and the distribution of the main groove and branch grooves on the moisture detection layer 2 matches the leaf veins; furthermore, the width of the main groove can be between 200±5 μm, and the width of the branch groove can be between 50±3 μm.

[0039] S3: A VOCs detection layer 3 is fabricated on the upper surface of the moisture detection layer 2. Then, a sensitive film is fabricated on the VOCs detection layer 3 by CVD process. The sensitive film is a reduced graphene oxide film or a silver nanowire composite film. Then, the sensitive film is defined into a paper-cut structure shape by photolithography process.

[0040] S4: A humidity detection layer 4 is fabricated on the lower surface of the lower substrate 11. Then, interdigitated electrodes are fabricated on the humidity detection layer 4 by magnetron sputtering. A PDMS dielectric layer is fabricated on the interdigitated electrodes by spin coating. The PDMS dielectric layer is then cured at 80°C. Finally, a second resistor is fabricated on the humidity detection layer 4, and the second resistor and the interdigitated electrodes form an RC oscillator. S5: Integrate the MCU control unit, wireless communication unit and power supply unit on the clamping substrate 12, and electrically connect the varistor, RC oscillator and sensitive film to the MCU main control unit. S6: Protective layers 5 are respectively provided on the upper surface of VOCs detection layer 3, the lower surface of humidity detection layer 4, and the clamping substrate 12; the water contact angle of the protective layer 5 is greater than 110°, and includes a polydichlorotoluene layer and a light-transmitting PDMS film arranged sequentially from the inside to the outside. The thickness of the polydichlorotoluene layer is 200nm, and the thickness of the light-transmitting PDMS film is between 10-30um. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A flexible sensor for plant detection, characterized in that, The upper substrate, the lower substrate and the clamping substrate are connected on the same side with the upper substrate and the lower substrate respectively; The upper surface of the upper substrate is provided with a moisture detection layer, a groove is opened on the moisture detection layer, a liquid metal is injected into the groove, the injected liquid metal is a pressure sensitive resistor, a first resistor is further provided on the moisture detection layer, the first resistor and the pressure sensitive resistor are connected in series to form a voltage division branch; The upper surface of the moisture detection layer is provided with a VOCs detection layer, the VOCs detection layer is provided with a sensitive film, the sensitive film is a reduced graphene oxide film or a silver nanowire composite film; The lower surface of the lower substrate is provided with a humidity detection layer, the humidity detection layer is provided with an interdigital electrode, the surface of the interdigital electrode is provided with a PDMS dielectric layer, the humidity detection layer is provided with a second resistor, the second resistor is electrically connected with the interdigital electrode to form an RC oscillator; The clamping substrate is respectively provided with an MCU control unit, a wireless communication unit and a power supply unit, the power supply unit is used for providing working voltage for the MCU control unit, the wireless communication unit and the voltage division branch; One end of the pressure sensitive resistor and the first resistor which are electrically connected is electrically connected with the analog-digital conversion input end of the MCU control unit, the MCU control unit is used for analog-digital conversion of the voltage of the pressure sensitive resistor, and the resistance value of the pressure sensitive resistor is calculated based on the voltage on the pressure sensitive resistor, the working voltage and the resistance value of the first resistor, and the moisture detection value is obtained based on the resistance value of the pressure sensitive resistor; The current output end of the MCU main control unit is connected with the sensitive film to input a constant current to the sensitive film, the analog-digital conversion input end of the MCU main control unit is also electrically connected with the sensitive film to obtain the voltage of the sensitive film, and the VOCs detection value is obtained based on the voltage of the sensitive film; The interrupt input end of the MCU main control unit is electrically connected with the output end of the RC oscillator, which is used for detecting the oscillation frequency of the RC oscillator, and the capacitance value of the interdigital electrode is obtained through the oscillation frequency of the RC oscillator, and the humidity detection value is obtained based on the capacitance value of the interdigital electrode; The MCU main control unit is electrically connected with the wireless communication unit, and the moisture detection value, the VOCs detection value and the humidity detection value are sent to a remote terminal through the wireless communication unit.

2. The flexible sensor for plant detection according to claim 1, wherein, The upper substrate, the lower substrate and the clamping substrate are prepared by mixing hydroxy-modified polydimethylsiloxane, silane coupling agent and self-healing accelerator at a ratio of 100:5:3; The sensitive film has a paper-cut structure shape.

3. The flexible sensor for plant detection according to claim 1, wherein, The groove includes a main groove and a branch groove, and the distribution positions of the main groove and the branch groove on the moisture detection layer match the vein structure of the leaf.

4. The flexible sensor for plant detection according to claim 1, wherein, The porosity of the PDMS dielectric layer is between 45%±3%, the pore size is between 1-5 μm, and the thickness is between 30-50 um.

5. The flexible sensor for plant detection according to any one of claims 1-4, wherein, A protective layer is respectively arranged on the upper surface of the VOCs detection layer, the lower surface of the humidity detection layer and the clamping substrate.

6. The flexible sensor for plant detection according to claim 5, wherein, The protective layer includes a poly-p-dichlorobenzene layer and a light-transmitting PDMS film arranged in sequence from inside to outside.

7. The flexible sensor for plant detection according to claim 6, wherein, The water contact angle of the protective layer is greater than 110°, the thickness of the parylene layer is between 150-200 nm, and the thickness of the light-transmitting PDMS film is between 10-30 um.

8. The flexible sensor for plant detection according to claim 1, wherein, The power supply unit includes a battery.

9. The flexible sensor for plant detection according to claim 8, wherein, The power supply unit includes a photovoltaic panel and a charge and discharge management unit for converting the output voltage of the photovoltaic panel into the charging voltage of the battery.

10. A method for making a flexible sensor for plant detection, characterized in that, The method comprises the following steps: S1: manufacturing an upper substrate, a lower substrate and a clamping substrate, wherein the clamping substrate is connected to the upper substrate and the lower substrate on the same side, specifically, first, mixing hydroxyl-modified polydimethylsiloxane, silane coupling agent and self-healing accelerator in a ratio of 100:5:3 to obtain a mixture; then placing the mixture into a mold corresponding to the upper substrate, the lower substrate and the clamping substrate; then curing the mold in an environment of 60°C for two hours; and finally demolding; S2: manufacturing a moisture detection layer on the upper surface of the upper substrate, then using a 1064nm laser to manufacture a groove on the moisture detection layer, then using a micro-injection pump to inject liquid metal into the groove under a pressure of 0.1MPa to form a piezoresistor; and finally manufacturing a first resistor on the moisture detection layer and connecting the first resistor in series with the piezoresistor; S3: manufacturing a VOCs detection layer on the upper surface of the moisture detection layer, then manufacturing a sensitive film on the VOCs detection layer through a CVD process, wherein the sensitive film is a reduced graphene oxide film or a silver nanowire composite film; then defining the sensitive film into a paper-cut structure shape through a photolithography process; S4: manufacturing a humidity detection layer on the lower surface of the lower substrate, then manufacturing interdigital electrodes on the humidity detection layer through a magnetron sputtering process, then manufacturing a PDMS dielectric layer on the interdigital electrodes through a spin coating method, then curing the PDMS dielectric layer in an environment of 80°C; and finally manufacturing a second resistor on the humidity detection layer and connecting the second resistor with the interdigital electrodes to form an RC oscillator; S5: integrating an MCU control unit, a wireless communication unit and a power supply unit for power supply on the clamping substrate, and electrically connecting the piezoresistor, the RC oscillator and the sensitive film with the MCU control unit; S6: providing a protective layer on the upper surface of the VOCs detection layer, on the lower surface of the humidity detection layer and on the clamping substrate; the water contact angle of the protective layer is greater than 110°, and the protective layer comprises a parylene layer and a light-transmitting PDMS film arranged from inside to outside, the thickness of the parylene layer is 200nm, and the thickness of the light-transmitting PDMS film is between 10-30 um.

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