Design of metasurface dual-gas sensor based on VO2

The traditional mine gas sensor is vulnerable to the influence of temperature and ambient humidity and other factors, resulting in low stability. In order to solve the above problem, based on the principle of local surface plasmon resonance (LSPR) and the phase change characteristics of vanadium dioxide (VO2), a kind of metasurface dual-gas sensor based on VO2 is designed. The sensor structure is composed of three layers, and the surface is composed of multi-layer metal-dielectric-metal (MDM) structure. According to the phase change characteristics of VO2, the metal plate is heated in the form of resistance heating by changing the applied bias voltage. The temperature of VO2 is carefully controlled, and the different states of VO2 are simulated by changing the conductivity of VO2. When VO2 is in a high-temperature metal state, the upper three layers form MDM structure. VO2 shows metal properties and excites local surface plasmon resonance (LSPR) at 1721.3 nm to realize methane detection. The sensor's absorptance reaches 94.3%, and the methane sensitivity reaches 4.21 nm/%. When VO2 is in a low-temperature insulation state, the lower three layers form MDM structure. LSPR is excited at 2694.6 nm to realize hydrogen detection. The sensor's absorptance reaches 95.9%, and the hydrogen sensitivity reaches 2.10 nm/%. When the environmental refractive index changes, the absorption peaks of VO2 in both states are red-shifted and linear,which can be used to detect the change of the environmental refractive index. In order to verify the feasibility of the sensor, six different concentrations of methane, hydrogen and four different environmental refractive indexes are simulated and analyzed. The results show that the metasurface dual-gas sensor based on VO2 can effectively detect methane and hydrogen with lower concentration. The sensitivity is greatly improved compared with the existing gas sensors. The error between the calculated and theoretical values of the resonant peak shift and the environmental refractive index change and the methane volume fraction change is very small. This indicates that the sensor has high accuracy. By analyzing the relationship between the environmental refractive index and the resonant wavelength, it is concluded that the sensor also has high detection sensitivity when the environmental refractive index changes.