Study On The Humidity Sensitive Properties Of Graphene Oxide And Its Application In The Capacitive Humidity Sensor

In this information age,a variety of data guides people’s production and life, which includes natural environment data. As one of most common and important environment data, humidity is not only closely related to people’s lives, but also have a wide range of applications in the area of medical devices, food quality detection, agriculture and animal husbandry, household appliances and other industries. With the continuous development of automatic control and data acquisition system, people have higher requirements on humidity sensors, it is both opportunity and challenge for humidity sensor industry. In recent years, new type of nano-materials, like graphene materials, have been widely used in the field of humidity sensors because of its excellent properties. Under the exploration of the comb electrodes and sensing materials, an adjustable GO(graphene oxide) capacitive humidity sensor with high sensitivity, short response time and humidity is proposed in this paper. The main work is as follows:First, theoretical analysis. In the choice of electrode structure, the existing typical comb electrodes and parallel plate electrode structure are compared in this paper. As for humidity sensitive material, this paper analyzes the advantages and disadvantages as humidity sensitive material of graphene-based composite materials, air, porous oxide and polymer. This paper also compares the resistive, capacitive and inductive sensors, and proposes a GO capacitive humidity sensor with a comb electrode.Second, modeling and simulation analysis.(1) Through the simulation results given by the software Materials Studio, this paper analyzes the dielectric constant(real and imaginary parts) and optical property changes(absorption rate and reflectivity) of Bilayer graphene surface after adsorbing three types of gases: H2 O, NH3, NO2. The results show that graphene-based composite materials can be used for the detection of oxidized gas.(2) Graphene, GO and GO-PMMA capacitive humidity sensor are simulated with COMSOL Multiphysics. The results show that GO is most sensitive to humidity.(3) Through the simulation and analysis of GO capacitive humidity sensor static response and dynamic response, the relationship between capacitance, sensitivity and comb electrode parameters is defined. At the same time, the simulation results show that the humidity sensor designed in this paper has better performance than traditional sensors. The relative humidity range is 0-100 %RH. When using the Grimes C.A model parameters, the sensitivity is 7680 f F/%RH, which is increased by 4.95 times compared with the classical structure of the sensor. On the other hand, the response time is 0.4 s, the response speed is higher than that of the traditional design significantly.