High sensitivity refractive index sensor based on metamaterial absorber

A metamaterial sensor is designed in this paper which can be used to detect the refractive index of an unknown dielectric loaded on the top surface of a metamaterial absorber. The resonant frequency of the absorber will be changed with various refractive indexes of the loaded dielectrics. Especially, the resonant frequency of the sensor is uniquely related to the refractive index of the unknown dielectric with the constant thickness, the linear relation of which is obtained by simulation fitting. A prototype of the absorber is manufactured and measured, which testify the design theory and simulation results. The S_fre of the proposed sensor is 0.3537 GHz/RIU, and the FoM can reach 11.0531 RIU⁻¹.