Humidity sensor based on perfect metamaterial absorber

We proposed a humidity sensor based on perfect metamaterial absorber. The sensor is composed of three layers, which are metallic particle array on the top, porous silicon in the middle layer and metallic film at the bottom. It is shown that the resonant wavelength displays significant red-shift with the increasing effective permittivity of porous silicon, which is influenced by the filling fraction of water condensation. Furthermore, the simulation results indicate that the refractive index sensitivity of absorber is high to 249 nm/RIU, which makes our structure be an ideal candidate for evaluating the humidity of environment.