A soil moisture sensor based on conductive hydrogel

Abstract

The utility model discloses a kind of soil humidity sensors based on conductive hydrogel, it is related to gel sensor technical field, comprising: substrate and sensor main body, the substrate is the substrate layer made of modified starch, two square metal electrode pieces are provided in sensor main body inner layer one end, the other end is provided with six pairs of ultraviolet photoetch interdigital electrode, by metal electrode piece and interdigital electrode jointly constitute the conductive layer of sensor, the response layer made of conductive hydrogel is provided in sensor main body outer layer, substrate layer, conductive layer and response layer jointly composed of the soil humidity sensor of this utility model. The utility model uses a kind of conductive, sensitivity high and degradable polymer hydrogel as the response material of soil humidity sensor, solves the problem that traditional capacitive soil humidity sensor is seriously polluted and low sensitivity is easily led to irrigation water too much or too little and causes water resource waste.

Description

Technical Field

[0001] This utility model relates to the field of gel sensor technology, specifically a soil moisture sensor based on conductive hydrogel. Background Technology

[0002] Hydrogels are polymeric materials with a three-dimensional network structure formed by cross-linked polymers. They contain numerous hydrophilic groups that, through hydrogen bonding and other interactions, can absorb tens or even hundreds of times their own weight in water or liquid. Their unique porous structure also determines their excellent water absorption capacity. Furthermore, the special three-dimensional network framework of hydrogels endows them with high hydration, excellent biocompatibility, good flexibility, and unique ease of modification. Currently, various types of hydrogels have been developed to meet the application requirements of various fields. Among them, conductive hydrogels are novel composite hydrogels that organically combine a hydrophilic matrix and a conductive medium, exhibiting good processability, high flexibility, and excellent electrochemical performance. They have broad application prospects in many fields such as electronic skin, biosensors, supercapacitors, and flexible wearable electronic devices, making them ideal materials for future flexible electronic devices.

[0003] Most current soil moisture sensors are widely used in agriculture, environmental monitoring, and other fields, but they still have many problems in practical use: such as susceptibility to environmental influences, resistive sensors are easily affected by soil salinity, and high salinity can lead to abnormal conductivity, resulting in distorted measurement results; insufficient measurement accuracy, resistive sensors have low resolution, making it difficult to meet the needs of high-precision agricultural irrigation; inconvenient installation and maintenance, insertion sensors may damage plant roots, affecting experiments or crop growth, and after long-term burial, they may become entangled in roots or suffer mechanical damage, making maintenance difficult; serious pollution from disposal, existing soil moisture sensors use plastic shells, which are difficult to degrade, causing serious soil pollution when disposed of.

[0004] To address the problems of traditional soil sensors, such as susceptibility to environmental interference, low measurement sensitivity, complex installation and maintenance, and serious pollution from disposal, it is necessary to develop a sensor based on new technologies. Utility Model Content

[0005] The purpose of this invention is to provide a soil moisture sensor based on conductive hydrogel to solve the problems mentioned in the background art.

[0006] The technical solution of this utility model is as follows:

[0007] A soil moisture sensor based on conductive hydrogel includes a substrate and a sensor body. The substrate is a base layer made of modified starch. Two square metal electrode sheets are disposed at one end of the inner layer of the sensor body, and six pairs of ultraviolet-etched interdigitated electrodes are disposed at the other end. The metal electrode sheets and interdigitated electrodes together constitute the conductive layer of the sensor. A response layer made of conductive hydrogel is disposed on the outer layer of the sensor body. The substrate layer, conductive layer, and response layer together constitute the soil moisture sensor.

[0008] According to this utility model, preferably, there are two metal electrode sheets, which are located on both sides of one end of the inner layer of the sensor body.

[0009] According to this invention, preferably, the metal electrode sheet is square in shape.

[0010] According to this utility model, preferably, the number of interdigitated electrodes is 6 pairs, arranged on the inner layer of the sensor body at the other end opposite to the metal electrode sheet.

[0011] According to this utility model, preferably, the interdigitated electrode is grid-shaped.

[0012] According to this utility model, preferably, the thickness of the metal electrode sheet in the inner layer of the sensor body is 5.0-6.0 mm.

[0013] According to this utility model, preferably, the thickness of the interdigitated electrodes in the inner layer of the sensor body is 2.8-3.2 mm.

[0014] According to this utility model, preferably, the thickness of the conductive hydrogel on the outer layer of the sensor body is 4.2-4.8 mm.

[0015] According to this utility model, preferably, the material of the base layer is modified starch, sodium alginate, clay, ceramic or fly ash.

[0016] According to this utility model, preferably, the conductive hydrogel response layer is made of MXene composite hydrogel, chitosan-based hydrogel, or polyacrylamide-based hydrogel.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] 1. The soil moisture sensor based on conductive hydrogel provided by this utility model uses conductive hydrogel as the response layer of the sensor. Since the hydrogel has a three-dimensional cross-linked network skeleton structure, after the introduction of conductive medium or other modified materials, it will produce obvious swelling or shrinkage behavior when the soil moisture changes, which further changes the capacitance value of the interdigitated electrodes. Therefore, the conductivity of the soil moisture sensor based on conductive hydrogel will change dynamically with the amount of water absorbed, and the response to humidity changes is more sensitive, with a resolution better than that of traditional resistive sensors.

[0019] 2. The soil moisture sensor based on conductive hydrogel provided by this utility model has stronger resistance to environmental interference. The conductive hydrogel works through an electron-ion mixed conductivity mechanism, and its conductivity is less affected by soil salinity. It can maintain stable measurement in high-salt soil, reducing calibration requirements. At the same time, the high water content and thermal buffering properties of the hydrogel can partially offset the influence of temperature fluctuations on the measurement, reducing the complexity of temperature compensation.

[0020] 3. The soil moisture sensor based on conductive hydrogel provided by this utility model has the advantages of simple installation and maintenance. The flexibility of the hydrogel allows it to wrap around plant roots or conform to irregular soil surfaces, reducing damage to the roots during installation. The non-invasive design measures soil moisture through surface contact, eliminating the need for deep burial and minimizing interference with soil structure. Furthermore, the conductive hydrogel possesses self-healing properties, allowing minor damage to recover on its own, reducing maintenance frequency.

[0021] 4. The soil moisture sensor based on conductive hydrogel provided by this utility model is environmentally friendly. The conductive hydrogel material used in the sensor response layer is non-toxic and degradable, which can reduce the negative impact on the soil ecology from long-term use. The modified starch material used in the sensor base layer can be naturally degraded, reducing sensor waste pollution. Attached Figure Description

[0022] Figure 1 This is a two-dimensional structural schematic diagram of the soil moisture sensor based on conductive hydrogel according to this utility model.

[0023] Figure 2 This is a three-dimensional structural diagram of the soil moisture sensor based on conductive hydrogel according to this utility model.

[0024] Figure 3 This is a schematic diagram of the layered structure of the soil moisture sensor based on conductive hydrogel according to this utility model.

[0025] In the figure, 1 is the substrate, 2 is the interdigitated electrode, 3 is the metal electrode sheet, and 4 is the conductive hydrogel. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Example 1

[0028] like Figure 1 , 2 As shown, a soil moisture sensor based on conductive hydrogel includes, from bottom to top, a substrate 1, an interdigitated electrode 2, a metal electrode sheet 3, and a conductive hydrogel 4. The interdigitated electrode 2 is disposed at one end of the substrate 1, and the metal electrode sheet 3 is disposed at the other end. The interdigitated electrode 2 is covered with conductive hydrogel 4. There are two metal electrode sheets 3, which are respectively located on both sides of the other end of the substrate 1 opposite to the interdigitated electrode 2.

[0029] The thickness of the interdigitated electrode 2 is 3 mm, the thickness of the metal electrode sheet 3 is 5.5 mm, and the thickness of the conductive hydrogel 4 is 4.5 mm.

[0030] The number of interdigitated electrodes 2 is 6 pairs, and the shape is grid-like; the number of metal electrode plates 3 is 2, and the shape is square.

[0031] The substrate 1 is made of modified starch; the conductive hydrogel 4 is made of MXene composite hydrogel.

[0032] Example 2

[0033] like Figure 3 As shown, the soil moisture sensor based on conductive hydrogel of this invention is divided into a base layer, a conductive layer, and a response layer from bottom to top. The base layer includes a substrate 1; the conductive layer includes interdigitated electrodes 2 and metal electrode sheets 3; the response layer includes conductive hydrogel 4; the base layer, conductive layer, and response layer together constitute the soil moisture sensor.

[0034] The conductive hydrogel 4 of the response layer is made of Mxene composite hydrogel, which has a three-dimensional cross-linked network framework structure. The hygroscopic monomers in the cross-linked network can rapidly adsorb and release water molecules, causing the gel structure to swell and shrink, reversibly changing the diameter of the conductive particles in the gel. This reversible swelling behavior changes the thickness of the gel layer, leading to a change in the effective relative permittivity of the gel material. With increasing humidity, the swelling behavior between the gel layers increases, the gel volume increases, and the effective relative permittivity increases, thus causing the sensor capacitance to increase with increasing humidity.

[0035] This invention relates to a soil moisture sensor based on conductive hydrogel. When the soil is in a humid environment, the conductive hydrogel 4 of the response layer senses changes in soil moisture and converts the soil moisture signal into an electrical signal. The interdigitated electrodes 2 and metal electrode 3 of the conductive layer receive the electrical signal and form a circuit with an external meter for transmission, thus completing the humidity sensing function.

Claims

1. A soil moisture sensor based on conductive hydrogel, characterized in that, It consists of a substrate and a sensor body; the sensor body includes an inner layer and an outer layer, the inner layer is provided with metal electrode sheets and interdigitated electrodes, and the outer layer is provided with conductive hydrogel.

2. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, There are two metal electrode sheets, located on both sides of one end of the inner layer of the sensor body.

3. The soil moisture sensor based on conductive hydrogel as described in claim 2, characterized in that, The metal electrode sheet is square in shape.

4. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, The number of interdigitated electrodes is 6 pairs, arranged on the inner layer of the sensor body at the other end opposite to the metal electrode sheet.

5. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, The interdigitated electrodes are grid-shaped.

6. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, The thickness of the metal electrode sheet in the inner layer of the sensor body is 5.0-6.0 mm.

7. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, The thickness of the interdigitated electrodes in the inner layer of the sensor body is 2.8-3.2 mm.

8. The soil moisture sensor based on conductive hydrogel as described in claim 1, characterized in that, The thickness of the conductive hydrogel on the outer layer of the sensor body is 4.2-4.8 mm.

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