A High Sensitivity Sandwich-Type Terahertz Metasurface Microfluidic Sensor for Directly Deteection of Aqueous Solutions

In order to solve the challenge that THz metasurface sensor has low sensitivity and hard to directly detect aqueous solution, a high sensitivity sandwich-type THz metasurface microfluidic sensor is numerically calculated and experimentally verified. The numerically calculated results show the sensor has a perfect absorption peak at 1.88 THz with a high Q-factor of 52.83 and a high sensitivity of 0.478 THz/RIU. The sensitivity of the proposed novel sensor is 3.51 times higher than that of the conventional transmission metasurface and 3.95 times higher than that of the conventional metasurface perfect absorber (MPA) structure. The measured results are basically consistent with the simulated results. The ∆f corresponding to 0.1 M, 0.5 M, 1.0 M and 1.5 M Na⁺ aqueous solution (pure water as reference) are 30 GHz, 60 GHz, 80 GHz and 130 GHz, respectively, which fully verifies the high sensing performance and stability of the proposed sensor.