Metamaterial optical refractive index sensor detected by the naked eye

An optical refractive index sensor that can be detected by the naked eye is presented in this paper. The sensor is developed based on the theory that metamaterials can completely absorb incident electric and magnetic field near its resonant frequencies. By inserting different mediums in the sensor or by dropping the mediums on the surface of the sensor, we detect the medium with a different refractive index through qualitative and quantitative analysis. The sensor is convenient for the detection of the liquid refractive index.