Highly sensitive and polarization-insensitive terahertz microfluidic biosensor based on gap plasmon model
Yanyan Liang, Qixiang Zhao, You Lv, Ruiqi Lu, Jialang Ling, Hang Mo, Mengshi Ma, Yanyan Zhang, Kunshan Mo
Abstract
The gap plasmon resonance can generate a local enhanced electric field and make the electromagnetic field energy mostly confined in the microfluidic, thereby increasing the interaction between the detection sample and terahertz wave. In this paper, a five-layer microfluidic terahertz biosensor based on gap plasmon resonance is presented. The simulation results show that the designed biosensor can realize a resonant absorption peak with near-perfect absorption at the frequency of 0.655 THz and high refractive index sensitivity of 191.3 GHz/RIU. In addition, the biosensor possesses the characteristics of polarization insensitivity and 50° incidence angle insensitivity due to the symmetry of the metal metasurface, which make the biosensor can be widely used in the biological label-free detection, medical trace element detection.