阅读说明：本技术 一种基于海泡石修饰碳材料的湿度传感器及其制备方法 (Humidity sensor based on sepiolite modified carbon material and preparation method thereof ) 是由 太惠玲 段再华 蒋亚东 袁震 吴英伟 赵秋妮 黄琦 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种基于海泡石修饰碳材料的湿度传感器及其制备方法,属于湿敏元件技术领域,具体涉及湿度传感器技术领域,以解决现有的湿度传感器湿度响应范围窄、检测湿度下限高、分辨率低的不足与缺陷,包括衬底,所述衬底表面含有叉指电极,所述衬底上涂覆有湿度敏感层,所述湿度敏感层完全覆盖所述叉指电极,所述湿度敏感层的材料包括海泡石、碳材料和溶剂,所述碳材料分散在所述溶剂中,所述海泡石、所述碳材料和所述溶剂的质量比为0-0.2:1:1-100,本申请的海泡石修饰碳材料湿度传感器具有宽湿度检测范围(0-95％RH)、低湿响应(2％RH)和高分辨(2％RH)优点。(The invention discloses a humidity sensor based on sepiolite modified carbon material and a preparation method thereof, belonging to the technical field of humidity sensitive elements, in particular to the technical field of humidity sensors, in order to solve the defects of narrow humidity response range, high lower limit of detected humidity and low resolution of the existing humidity sensor, comprising a substrate, the surface of the substrate contains interdigital electrodes, a humidity sensitive layer is coated on the substrate and completely covers the interdigital electrodes, the material of the humidity sensitive layer comprises sepiolite, a carbon material and a solvent, wherein the carbon material is dispersed in the solvent, the mass ratio of the sepiolite to the carbon material to the solvent is 0-0.2:1:1-100, and the sepiolite-modified carbon material humidity sensor has the advantages of wide humidity detection range (0-95% RH), low humidity response (2% RH) and high resolution (2% RH).)

1. The utility model provides a humidity sensor based on sepiolite modification carbon material which characterized in that: the humidity sensitive layer is coated on the substrate and completely covers the interdigital electrode, the material of the humidity sensitive layer comprises sepiolite, a carbon material and a solvent, the carbon material is dispersed in the solvent, and the mass ratio of the sepiolite to the carbon material to the solvent is 0-0.2:1: 1-100.

2. The humidity sensor based on sepiolite-modified carbon material according to claim 1, wherein: the mass ratio of the sepiolite to the carbon material to the solvent is 0.01-0.1:1: 1-100.

3. The humidity sensor according to claim 1 or 2, wherein the carbon material modified by sepiolite comprises: the carbon material is one or a combination of more of carbon ink, carbon black, carbon nano tubes, graphene, graphite alkyne and fullerene.

4. The humidity sensor according to claim 1 or 2, wherein the carbon material modified by sepiolite comprises: the solvent is one or a combination of more of deionized water, glycerol, polyvinyl alcohol, ethylene glycol, glycerol, dimethyl silicone oil, a dispersing agent NNO and polyvinyl acetate emulsion.

5. The humidity sensor based on sepiolite-modified carbon material according to claim 1, wherein: the thickness of the humidity sensitive layer is 10-100 μm.

6. The humidity sensor based on sepiolite-modified carbon material according to claim 1, wherein: the number of the interdigital electrodes is 1-10 pairs, and the interdigital distance of each pair of the interdigital electrodes is 50-500 mu m.

7. The humidity sensor based on sepiolite-modified carbon material according to claim 6, wherein: the number of the interdigital electrodes is 5 pairs, and the interdigital distance of each pair of the interdigital electrodes is 250 μm.

8. The humidity sensor based on sepiolite-modified carbon material according to claim 1, wherein: the substrate is one of polyethylene glycol terephthalate, polyimide, silicon or aluminum oxide.

9. A method for preparing a humidity sensor based on sepiolite-modified carbon material according to any of claims 1 to 8, comprising the following steps:

step 1, uniformly mixing a carbon material and a solvent according to the mass ratio to obtain a uniformly dispersed carbon material solution;

step 2, mixing the sepiolite with the carbon material solution uniformly to obtain a sepiolite-modified carbon material solution;

step 3, coating the sepiolite-modified carbon material solution on a substrate containing the interdigital electrode to form a humidity sensitive layer;

and 4, drying the substrate with the humidity sensitive layer at the temperature of 20-100 ℃ for 1-5 hours to obtain the sepiolite-modified carbon material humidity sensor.

10. The method of claim 9, wherein: the coating in the step 3 comprises brush coating, blade coating by a scraper, spin coating, drop coating, air spraying or dipping.

Technical Field

The invention discloses a humidity sensor based on a sepiolite modified carbon material and a preparation method thereof, belongs to the technical field of humidity sensitive elements, and particularly relates to the technical field of humidity sensors.

Background

Humidity is a physical quantity for representing the dryness of the atmosphere and is an important and common measurement parameter in the industrial and agricultural production process. The humidity sensor is a device type device capable of converting humidity into electric quantity in a certain proportional relation with the humidity and outputting the electric quantity. The main characteristic parameters include humidity range, humidity sensing characteristic quantity, sensitivity, humidity temperature coefficient, response time and humidity hysteresis return difference. The development of the humidity sensor plays an important role in ensuring the product quality, improving the production efficiency, saving energy, ensuring the production safety and promoting the development of national economy.

The working principle of the resistance type humidity sensor is that after the humidity sensitive material adsorbs water molecules, the adsorbed water molecules are ionized to form conductive ions; further, under a high-humidity environment, a large amount of adsorbed water molecules form a continuous water film, so that ion transmission is promoted, the conductivity of the humidity sensitive material is increased, and the resistance of the humidity sensor is reduced to generate humidity sensitive response. Generally, for a humidity sensor of a resistance decreasing type with an increase in humidity, a large amount of water molecules needs to be adsorbed to generate an ion transport condition, and thus, the humidity sensor is generally insensitive to low humidity, and limits a humidity detection range and a low humidity detection capability thereof. In addition, the working principle of a resistance type humidity sensor is to utilize the hygroscopic expansion effect and the conduction blocking effect of a humidity sensitive material with good conductivity, and the resistance of the humidity sensor is increased after water molecules are adsorbed (Qiani ZHao, Zhen Yuan, ZaihuaDuan, Yang Jiang, Xian Li, Zhemin Li, Huilingtai, Sensors and Actuators B: Chemical,289(2019)182 + 185), which is expected to improve the humidity detection range of the humidity sensor.

The humidity sensor has important application in the fields of industry, agriculture, medical treatment, aerospace, home furnishing and the like, and along with the expansion of the application range of the humidity sensor, the development of the humidity sensor with wide humidity detection range, low humidity response and high resolution is urgently needed.

Disclosure of Invention

The invention aims to: the humidity sensor based on the sepiolite modified carbon material and the preparation method thereof are provided, and the defects that the existing humidity sensor is narrow in humidity response range, high in lower limit of detected humidity and low in resolution are overcome.

The technical scheme adopted by the invention is as follows:

the humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein an interdigital electrode is arranged on the surface of the substrate, a humidity sensitive layer is coated on the substrate and completely covers the interdigital electrode, the humidity sensitive layer is made of sepiolite, a carbon material and a solvent, the carbon material is dispersed in the solvent, and the mass ratio of the sepiolite to the carbon material to the solvent is 0-0.2:1: 1-100.

In the technical scheme of the application, sepiolite (Mg8[ Si2O30] (OH) 4.12H 2O), a water-containing magnesium-rich silicate clay mineral with a layer chain structure has the characteristics of no toxicity, no harm, good plasticity, large specific surface, multiple pore channels, strong water absorption, good thermal stability and the like, the sepiolite modified carbon material humidity sensor has the advantages of wide humidity detection range (0-95% RH), low humidity response (2% RH) and high resolution (2% RH).

Preferably, the mass ratio of the sepiolite to the carbon material to the solvent is 0.01-0.1:1: 1-100.

Preferably, the carbon material is one or more of carbon ink, carbon black, carbon nanotube, graphene, graphite alkyne and fullerene.

Preferably, the solvent is one or a combination of more of deionized water, glycerol, polyvinyl alcohol, ethylene glycol, glycerol, dimethyl silicone oil, a dispersant NNO and polyvinyl acetate emulsion.

Preferably, the humidity sensitive layer has a thickness of 10 to 100 μm.

Preferably, the number of the interdigital electrodes is 1-10 pairs, and the interdigital distance of each pair of the interdigital electrodes is 50-500 μm.

More preferably, the number of the interdigital electrodes is 5 pairs, and the interdigital distance of each pair of the interdigital electrodes is 250 μm.

Preferably, the substrate is one of polyethylene terephthalate, polyimide, silicon or aluminum oxide.

A preparation method of a humidity sensor based on a sepiolite modified carbon material comprises the following steps:

step 1, uniformly mixing a carbon material and a solvent according to the mass ratio to obtain a uniformly dispersed carbon material solution;

step 2, mixing the sepiolite with the carbon material solution uniformly to obtain a sepiolite-modified carbon material solution;

step 3, coating the sepiolite-modified carbon material solution on a substrate containing the interdigital electrode to form a humidity sensitive layer;

and 4, drying the substrate with the humidity sensitive layer at the temperature of 20-100 ℃ for 1-5 hours to obtain the sepiolite-modified carbon material humidity sensor.

Preferably, the coating in step 3 comprises brush coating, doctor blade coating, spin coating, drop coating, air-jet coating, or dipping.

Preferably, the substrate having the humidity sensitive layer is dried at 60 ℃ for 2 hours in step 4.

The preparation method of the humidity sensor is characterized in that the sepiolite-modified carbon material solution is uniformly coated on a substrate with interdigital electrodes and is dried, and the preparation method of the humidity sensor is completed.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. in the invention, the strong hydrophilicity of the sepiolite is utilized to realize the adsorption of low-humidity (2% RH) water molecules;

2. according to the invention, the humidity sensor with positive sensitivity coefficient is prepared by utilizing the characteristic that the resistance rises after the carbon material adsorbs water molecules;

3. in the invention, the sepiolite modified carbon material humidity sensor has the advantages of wide humidity detection range (0-95% RH), low humidity response (2% RH) and high resolution (2% RH);

4. the humidity sensor has the advantages of simple structure, simple and convenient preparation method and low cost, and is beneficial to large-scale manufacture, popularization and application.

Drawings

FIG. 1 is a scanning electron microscope image of sepiolite according to the invention;

FIG. 2 is a scanning electron microscope image of carbon ink according to the present invention;

FIG. 3 is a real-time resistance change curve of the sepiolite-modified carbon ink humidity sensor under different humidities, and the inset is a real-time resistance change curve in the low humidity range (0% -10% RH);

fig. 4 is a response-time curve diagram of the sepiolite-modified carbon ink humidity sensor under the switching of 0% and 95% RH.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

Based on embodiment 1, the humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein the surface of the substrate contains interdigital electrodes, a humidity sensitive layer is coated on the substrate, the humidity sensitive layer completely covers the interdigital electrodes, the humidity sensitive layer is made of sepiolite, carbon black and a solvent, the carbon black is dispersed in the solvent, the mass ratio of the sepiolite to the carbon black to the solvent is 0.1:1:100, and the solvent comprises, by weight, deionized water (1000 parts), glycerol (50 parts), polyvinyl acetate emulsion (10 parts) and a dispersant NNO (1 part); the thickness of the humidity sensitive layer is 20 mu m; the number of the interdigital electrodes is 1 pair, and the interdigital distance of each pair of the interdigital electrodes is 100 mu m; the substrate is silicon.

A preparation method of a humidity sensor based on a sepiolite modified carbon material comprises the following steps:

step 1, uniformly mixing carbon black and a solvent according to the mass ratio to obtain a uniformly dispersed carbon material solution;

step 2, mixing the sepiolite with the carbon material solution uniformly to obtain a sepiolite-modified carbon material solution;

step 3, coating (spin coating) the sepiolite modified carbon material solution on a substrate containing the interdigital electrode to form a humidity sensitive layer;

and 4, drying the substrate with the humidity sensitive layer at 60 ℃ for 2 hours to obtain the sepiolite-modified carbon material humidity sensor.

Example 2

The humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein interdigital electrodes are arranged on the surface of the substrate, a humidity sensitive layer is coated on the substrate, the humidity sensitive layer completely covers the interdigital electrodes, the humidity sensitive layer is made of sepiolite, carbon nano tubes and a solvent, and the mass ratio of the sepiolite to the carbon nano tubes to the solvent is 0.1:1:100, respectively; the solvent comprises, by weight, 1000 parts of deionized water (1000 parts), 50 parts of glycerol (50 parts), 5 parts of polyvinyl acetate emulsion (5 parts) and 1 part of dispersant NNO (1 part); the thickness of the humidity sensitive layer is 50 μm; the number of the interdigital electrodes is 10, and the interdigital distance of each pair of the interdigital electrodes is 100 mu m; the substrate is polyimide.

The preparation method is the same as example 1.

Example 3

The humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein an interdigital electrode is arranged on the surface of the substrate, a humidity sensitive layer is coated on the substrate, the humidity sensitive layer completely covers the interdigital electrode, the humidity sensitive layer is made of sepiolite, carbon ink and a solvent, and the mass ratio of the sepiolite to the carbon ink to the solvent is 0.01:1: 1; the solvent is deionized water; the thickness of the humidity sensitive layer is 50 μm; the number of the interdigital electrodes is 10, and the interdigital distance of each pair of the interdigital electrodes is 100 mu m; the substrate is polyethylene terephthalate.

A preparation method of a humidity sensor based on a sepiolite modified carbon material comprises the following steps:

step 1, uniformly mixing carbon ink and deionized water according to a mass ratio of 1:1 to obtain a uniformly dispersed carbon ink solution;

step 2, mixing the sepiolite with the carbon material solution uniformly to obtain a sepiolite-modified carbon material solution;

step 3, coating (soaking) the sepiolite-modified carbon material solution on a substrate containing the interdigital electrode to form a humidity sensitive layer;

and 4, drying the substrate with the humidity sensitive layer at 50 ℃ for 3 hours to obtain the sepiolite-modified carbon material humidity sensor.

Example 4

Based on embodiment 1, the humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein the surface of the substrate contains interdigital electrodes, a humidity sensitive layer is coated on the substrate, the humidity sensitive layer completely covers the interdigital electrodes, the humidity sensitive layer is made of sepiolite, graphene and a solvent, the graphene is dispersed in the solvent, the mass ratio of the sepiolite to the graphene to the solvent is 0.01:1:80, and the solvent comprises, by weight, deionized water (800 parts), glycerol (40 parts), polyvinyl acetate emulsion (8 parts) and a dispersing agent NNO (0.8 part); the thickness of the humidity sensitive layer is 20 mu m; the number of the interdigital electrodes is 1 pair, and the interdigital distance of each pair of the interdigital electrodes is 100 mu m; the substrate is aluminum oxide.

The preparation method is the same as example 1.

Example 5

Based on embodiment 1, the humidity sensor based on the sepiolite-modified carbon material comprises a substrate, wherein the surface of the substrate contains interdigital electrodes, a humidity sensitive layer is coated on the substrate, the humidity sensitive layer completely covers the interdigital electrodes, the humidity sensitive layer is made of materials including sepiolite, graphite alkyne and a solvent, the graphite alkyne is dispersed in the solvent, the mass ratio of the sepiolite to the graphite alkyne to the solvent is 0.1:1:50, and the solvent comprises, by weight, deionized water (500 parts), glycerol (25 parts), polyvinyl acetate emulsion (5 parts) and a dispersing agent NNO (0.5 part); the thickness of the humidity sensitive layer is 100 mu m; the number of the interdigital electrodes is 10, and the interdigital distance of each pair of the interdigital electrodes is 100 mu m; the substrate is polyethylene terephthalate.

The preparation method is the same as example 1.

Example 6

Based on example 3, the mass ratio of the sepiolite to the carbon ink to the deionized water is 0:1: 1.

Test examples

As shown in fig. 1 to 4, the humidity sensor based on the sepiolite-modified carbon material prepared in example 3 was tested for performance according to the method disclosed in the art, which specifically comprises: testing resistance signals of the humidity sensor prepared by the method by using a resistance testing instrument, wherein atmospheres with different Relative Humidities (RH) are obtained by a bubbling method, and the relative humidities comprise 0%, 2%, 4%, 6%, 8%, 10%, 20%, 40%, 60%, 80% and 95% RH;

in the technical scheme of the invention, the sepiolite is commercially available, and the shape of the sepiolite is shown in figure 1;

in order to embody the characteristic of low cost of raw materials, the carbon material is selected from carbon ink for daily writing on the market, wherein the carbon ink contains carbon nano-particles (figure 2);

as shown in fig. 3, the humidity sensor based on the sepiolite-modified carbon material measured in the test example has a wide humidity detection range (0 to 95% RH), an extremely low lower detection limit (2% RH), and a high humidity response resolution (2% RH);

it is shown from the response-time graph of the sepiolite-modified carbon material of fig. 4 at 0% and 95% relative humidity switch that the humidity sensor based on attapulgite has good response recovery characteristics.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.