阅读说明：本技术 一种基于埃洛石纳米管的湿度传感器及其制备方法 (Humidity sensor based on halloysite nanotube and preparation method thereof ) 是由 太惠玲 段再华 蒋亚东 赵秋妮 黄琦 谢光忠 杜晓松 于 2019-10-17 设计创作，主要内容包括：本发明提供了一种基于埃洛石纳米管的湿度传感器及其制备方法,属于湿敏元件及其制备技术领域,一种基于埃洛石纳米管的湿度传感器,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感应层,所述湿度感应层完全覆盖所述叉指电极,所述湿度感应层是埃洛石纳米管。本申请的一种基于埃洛石纳米管的湿度传感器具有大的湿度响应,阻抗变化为5个数量级；检测范围宽,可以检测0％-91.5％范围的相对湿度；响应时间快,不超过1秒；具有原材料资源丰富、成本低廉、绿色环保,器件制备工艺简单的优点,具有较好的实际应用价值。(The invention provides a humidity sensor based on a halloysite nanotube and a preparation method thereof, belongs to the technical field of humidity sensitive elements and preparation thereof, and discloses a humidity sensor based on a halloysite nanotube. The halloysite nanotube-based humidity sensor has large humidity response, and impedance change is 5 orders of magnitude; the detection range is wide, and the relative humidity in the range of 0-91.5% can be detected; the response time is fast and is not more than 1 second; the method has the advantages of rich raw material resources, low cost, environmental protection and simple device preparation process, and has better practical application value.)

1. A humidity sensor based on halloysite nanotubes, comprising: the interdigital electrode structure comprises a substrate, wherein the surface of the substrate contains interdigital electrodes, a humidity induction layer is coated on the substrate and completely covers the interdigital electrodes, the humidity induction layer is made of a halloysite nanotube and a solvent, and the mass ratio of the halloysite nanotube to the solvent is 1: 1-10.

2. The halloysite nanotube based humidity sensor of claim 1, wherein: the mass ratio of the halloysite nanotubes to the solvent is 1: 3.

3. The halloysite nanotube based humidity sensor of claim 1, wherein: the solvent is deionized water, ethanol or acetone.

4. The halloysite nanotube based humidity sensor of claim 1, wherein: the thickness of the humidity sensing layer is 10-100 mu m.

5. The halloysite nanotube based humidity sensor of 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.

6. The halloysite nanotube based humidity sensor of claim 5, wherein: the number of the interdigital electrodes is 5 pairs, and the interdigital distance of each pair of the interdigital electrodes is 150 mu m.

7. The halloysite nanotube based humidity sensor of claim 1, wherein: the substrate is one of aluminum oxide, silicon, polyimide, polyetherimide, paper or fabric.

8. Method for the preparation of a humidity sensor based on halloysite nanotubes according to any of claims 1 to 7, characterized in that it comprises the following steps:

(1) uniformly mixing the halloysite nanotube with a solvent to obtain a halloysite nanotube solution;

(2) coating the halloysite nanotube solution on a substrate containing interdigital electrodes to form a humidity sensing layer;

(3) and (3) drying the substrate with the humidity sensing layer at the temperature of 20-100 ℃ for 1-5 hours to obtain the halloysite nanotube humidity sensor.

9. The method of claim 8, wherein the step (2) is performed by pen coating, spin coating, drop coating, air spraying, or dipping.

10. The method of claim 8, wherein in the step (3), the substrate having the humidity sensing layer is dried at 70 ℃ for 2 hours.

Technical Field

The invention relates to the technical field of humidity-sensitive elements and preparation thereof, in particular to a humidity sensor based on halloysite nanotubes and a preparation method thereof.

Background

Moisture sensing technology has been developed for over 200 years, and the recognition of moisture sensors began with the successful development of dip-coated LiCl moisture sensors in 1938 us f.w.dumcore, since which several dozen moisture sensors and sensors have been developed.

The relative humidity is used as an important environmental parameter in places such as home, industry, agriculture and medical treatment, and it is necessary to develop a high-performance and low-cost humidity sensor to accurately monitor the humidity.

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 moisture-sensitive material serves as the core of the humidity sensor, and is characterized by containing hydrophilic functional groups and having hydrophilic characteristics.

Chinese patent 200810037939.X discloses a preparation method of a Ni/Si nanowire array and a micro-nano humidity sensor based on the nanowire array. The device is to manufacture a large-area silicon nanowire array on an N-type silicon substrate by adopting an electrochemical etching technology, and then to electrolessly deposit a nickel film on the array. The structure has large length-diameter ratio and specific surface area, and the microstructure is unique, so that the structure can generate unique physical and chemical properties, and the adsorption and desorption capacity of the structure to water molecules is better than that of a pure silicon nanowire array. The preparation process is complex and the process control is difficult.

Chinese patent CN200810046860.3 discloses a method for preparing a nano metal oxide ceramic thin/thick film, which sequentially comprises the steps of preparing mixed solution containing metal cations, organic monomers, a cross-linking agent and an initiator ①, catalyzing and initiating ② to form gel, preparing slurry suitable for film coating ③, coating ④ and carrying out ⑤ heat treatment, wherein the method takes cheap inorganic salt as raw materials, and has the advantages of simple process and easy operationThe method has high efficiency and good repeatability, and the size of the metal oxide particles and the thickness of the film can be easily controlled by adjusting process parameters. Can effectively inhibit the mutual contact and agglomeration of particles, and simultaneously makes up the defects of high requirement and high cost of common film preparation technology on experimental equipment. Has stronger universality and universality, and is also suitable for preparing the composite multilayer nano metal oxide ceramic thin/thick film. However, since tin oxide itself is easily reacted with NO, NO₂，CO，H₂，H₂S and C₂H₅Other gases such as OH react chemically, and thus have poor selectivity for humidity detection.

In order to develop a high-performance and low-cost humidity sensor, on one hand, researchers improve the humidity-sensitive performance of the traditional humidity-sensitive material by using a novel preparation process; on the other hand, the performance of the humidity sensor is improved by using the novel humidity sensitive material. The humidity sensors reported at present generally do not allow for a compromise between high performance and low cost.

Disclosure of Invention

Aiming at the defects that the existing humidity sensor generally cannot give consideration to high performance and low cost, the invention provides a humidity sensor based on halloysite nanotubes and a preparation method thereof.

The humidity sensor based on the halloysite nanotube comprises a substrate, wherein the surface of the substrate contains interdigital electrodes, a humidity sensing layer is coated on the substrate, the humidity sensing layer completely covers the interdigital electrodes, the humidity sensing layer is made of the halloysite nanotube and a solvent, and the mass ratio of the halloysite nanotube to the solvent is 1: 1-10.

In the technical scheme of the application: the halloysite is a natural tubular silicate mineral and structurally consists of a dioctahedral structure with a 1:1 structural unit layer, and the structural characteristics determine that a large number of pore channels exist in the halloysite, the surface of the halloysite has Si-OH and negative charges, the halloysite has good heat resistance, acid and alkali resistance, high water absorption and large specific surface area; by utilizing the large specific surface area and good hydrophilic property of the halloysite nanotube, the halloysite nanotube and a solvent are uniformly mixed according to the mass ratio and then coated on the surface of the substrate and the surface of the interdigital electrode to form a humidity sensing layer, the impedance change of the humidity sensor is 5 orders of magnitude, the detection range is wide, and the relative humidity in the range of 0-91.5% can be detected; the response time is fast and is not more than 1 second; the humidity sensor has the advantages of rich raw material resources, low cost, environmental protection and simple device preparation process, and overcomes the defect that the conventional humidity sensor cannot give consideration to high performance and low cost generally.

Preferably, the mass ratio of the halloysite nanotubes to the solvent is 1: 3.

Preferably, the solvent is deionized water, ethanol or acetone.

Preferably, the thickness of the humidity sensitive layer is 10-100 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 150 μm.

Preferably, the substrate is one of alumina, silicon, polyimide, polyetherimide, paper or fabric.

A preparation method of a humidity sensor based on halloysite nanotubes comprises the following steps:

(1) uniformly mixing the halloysite nanotube with a solvent to obtain a halloysite nanotube solution;

(2) coating the halloysite nanotube solution on a substrate containing interdigital electrodes to form a humidity sensing layer;

(3) and (3) drying the substrate with the humidity sensing layer at the temperature of 20-100 ℃ for 1-5 hours to obtain the halloysite nanotube humidity sensor.

Preferably, the coating in step (2) is performed by pen coating, spin coating, drop coating, air spraying, or dipping.

Preferably, in the step (3), the substrate having the humidity-sensitive layer is dried at 70 ℃ for 2 hours.

In the technical scheme of the application, the halloysite nanotubes are commercially available.

Compared with the prior art, the invention has the beneficial effects that:

(1) the humidity sensor has the advantages that the impedance change is 5 orders of magnitude, the response speed is high and is not more than 1 second, the humidity sensor has good response recovery characteristics, and the humidity sensor has high performance and low cost;

(2) the halloysite nanotube solution is uniformly coated on a substrate with interdigital electrodes, and the preparation of the halloysite nanotube humidity sensor is completed after drying, so that the preparation method is simple and convenient, the energy consumption is low, and the cost is low;

(3) the halloysite nanotube humidity sensor is simple in structure and beneficial to large-scale manufacturing, popularization and use;

(4) the halloysite nanotube is applied to a humidity sensor as a humidity sensing layer for the first time, and has important significance for developing a humidity sensor with simple structure, simple and convenient preparation technology, low cost and high performance.

Drawings

FIG. 1 is a transmission electron microscope image of a halloysite nanotube of the invention;

FIG. 2 is a graph of impedance versus relative humidity for a halloysite nanotube humidity sensor of the invention;

FIG. 3 is a graph of the wet hysteresis of a halloysite nanotube humidity sensor of the invention;

fig. 4 is a graph of 10 cycle response versus time for a halloysite nanotube humidity sensor of the invention at 0% and 91.5% relative humidity switching.

Fig. 5 is a graph of linear response versus time for a halloysite nanotube humidity sensor of the invention at 0% and 91.5% relative humidity switching.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to specific embodiments.