Preparation And Sensitive Properties Of Flexible Humidity Sensor

Humidity is closely related to people's production and life.Humidity sensors have been widely used in many fields such as meteorological monitoring,pharmaceutical manufacturing,and agricultural production.With the advent of the Internet era,the requirements for various aspects of humidity sensors are getting higher and higher,and the progress and development of humidity detection technology is continuously promoted.In recent years,researchers have not only limited to improving the sensitivity of humidity sensors,but also focused on combining humidity sensors with flexible electronics to develop flexible humidity sensors.Based on the research status of flexible humidity sensor,we prepared a resistive flexible humidity sensor based on reduced graphene oxide?rGO?/tungsten disulfide?WS₂?composite film and a self-powered flexible humidity sensor based on natural polymer material chitosan?CTS?/Amino-modified graphene?GO-NH₂?composite film.Combined with the morphology analysis and spectral analysis of the material,the corresponding humidity sensitivity mechanism is established.The main contents of the thesis research are as follows:?1?Flexible resistive humidity sensors based on single rGO film and rGO/WS₂layered composite film were prepared by air-jet and thermal reduction at different temperatures.The single rGO and rGO/WS₂ composite film were characterized by SEM,UV-Vis,Raman and XRD.Characterization analysis showed that the surface of a single rGO film is continuous and has obvious wrinkles,while the surface of the rGO/WS₂layered composite film is unevenly distributed with WS₂ nanosheets.The interlayer coupling structure of WS₂ prepared by ultrasonic stripping is a few layer coupling.Annealing has no significant effect on the WS₂ structure,as the annealing temperature increases,the degree of reduction of rGO increases,and there is an interaction between the WS₂ nanoparticle film layer and the rGO film layer in the layered composite film.The humidity sensitivity test showed that the composite film annealed at 220°C have the best humidity sensitivity response.The humidity response of rGO/WS₂ layered composite films is better than that of single layer rGO films.The humidity response of rGO/WS₂layered composite films is about 2.33 times higher than that of single layer rGO films,and it has good repeatability and stability.Finally,we briefly analyzed the humidity sensing mechanism of the composite film.It is considered that the P-N junction is formed on the contact interface between rGO and WS₂,and the formation of the heterojunction greatly improves the humidity sensing properties of the composite film.?2?CTS/GO-NH₂ composite films were deposited on PET-based electrodes by solution blending method and spray method and the self-powered CTS/GO-NH₂composite film humidity sensor was prepared based on a structure of Triboelectric Nano-generator?TENG?.The composite film was characterized by SEM,FTIR and XRD.The analysis results showed that the doped GO-NH₂ is dispersed in the CTS film in the form of sheet and does not chemically react with CTS,this dispersion enhances the interaction between CTS and GO-NH₂.After testing the humidity sensitivity of the composite,it was found that the responsiveness and linearity of the humidity sensitivity of the composite film were affected by the doping amount of GO-NH₂.The results of humidity sensitivity test show that changing the doping amount of GO-NH₂ will affect the responsibility and linearity of the composite film.The CTS/GO-NH₂ composite film with a GO-NH₂ doping concentration of 0.7 mg/ml has the best linearity and its responsibility has also improved Compared with pure CTS.Moreover,the doped composites have low hysteresis and good repeatability.Finally,we briefly analyzed the humidity-sensitive properties mechanism of the self-powered humidity sensor.