Study On Resistive-type Humidity Sensors Based On Several Kinds Of Low-dimensional Mesoporous Materials

With the development of science and technology, Internet of things which is thethird wave of information technology after computer and Internet is moving into thefields of human production and living. According to the principle of generation,transmission, processing and application of information, the Internet of things can bedivided into four layers: cognitive recognition layer, network building layer,management-service layer and integrated application layer. The perceptionrecognition layer is most basic level of things. And it is also the union combining theinformation world with the things world. As an important part of the perceptualrecognition layer, sensors is supporting the normal operation of the whole level. Withthe development of science and technology, sensors have permeated every field ofhuman production and living, such as industrial, agricultural production, medical,military defense, and environmental protection. It is called one of the three pillars ofinformation technology, and playing a key role in the process of information.Humidity sensor as a device of measurement environment humidity change, is a veryimportant member of the sensor family.Resistive and capacitive humidity sensors are two kinds of humidity sensorswhich are based on the electrical measurement. They have got extensive attention ofscientists due to the high sensitivity, accuracy and easy integration. There are manyfactors that can affect the performance of humidity sensor, the choice of humiditysensitive material should be the most important one. One-dimensional nanomaterialsand ordered mesoporous material is two very important member of the material family. The two materials have received widely attention in the field of chemical sensing andcatalysis because of the unique properties such as high specific surface area, highlength-diameter ratio, axial electron transmission and radial quantum confined etc. Inour works, the one-dimensional nanostructures was combined with orderedmesoporous structure. Through different methods, several kinds of materials with thetwo structures have been synthesized. And the humidity sensors based on thematerials have been also produced.In the second chapter, the KIT-6material with three-dimensional orderedmesoporous structure was prepared by “liquid crystal soft template” method. And theLiCl/KIT-6composite with excellent humidity sensitive performance was preparedthrough the adoption of LiCl. Results show that the adoption of moderate LiCl caneffectively improve the humidity sensitive properties of Eigen state KIT-6, such as thebad response to low relative humidity and small measuring range.In the third chapter, the silica nanofiber with two-dimensional orderly six-partymesoporous channel structure was prepared by electrospinning in combination withthe soft templates F127and CTAB. And the humidity sensitive properties werestudied. We mainly discussed the influence to the humidity sensitive performance ofthe two cases which is introducing mesoporous structure into one-dimensional silicamaterials or not. Results show that the introduction of the ordered mesoporousstructure can effectively improve the eigen state humidity sensitive properties.In the fourth chapter, we firstly prepared MCM-48mesoporous silicananoparticles materials by “liquid crystal soft template” method mentioned in thesecond chapter. And then the MCM-48nanofiber was synthesized through colloidelectrospinning. The humidity sensing properties were also discussed. Results showthat compared with MCM-48mesoporous silica nanoparticles, the MCM-48nanofiberexhibited better humidity sensing performance on humidity measurement range,hysteresis characteristics and response-recovery property.In the fifth chapter, the method mentioned in the third chapter was expanded toprepare ordered mesoporous metal oxides nanofiber such as Ba0.77Sr0.23TiO3. Wemainly discussed the influence to the humidity sensitive performance of the two cases which is introducing mesoporous structure into one-dimensional Ba0.77Sr0.23TiO3materials or not. Results show that the introduction of the ordered mesoporousstructure can effectively improve the humidity sensitive properties of Ba0.77Sr0.23TiO3nanofiber.Our work forces on the combination of ordered mesoporous structure andone-dimensional nanostructure. Through the research to humidity performance of thehumidity sensor, it is found that the combination of one-dimensional nanostructuresand ordered mesoporous structure can significantly improve the humidity sensitiveproperties.