High-performance terahertz microfluidic sensors based on Fabry–Perot resonance

Abstract

The Fabry–Perot resonance within a microfluidic channel plays a crucial role in enhancing electromagnetic field strength, facilitating intensified interactions between terahertz waves and samples. In this paper, we introduce two terahertz microfluidic sensors based on Fabry–Perot resonance, each exhibiting dual resonant peaks for non-destructive detection. The first sensor features a periodic arrangement of three "I-type" structures, generating resonant peaks within the frequency range of 0.2–1.2 THz. These peaks correspond to absorption rates of 99.17% and 99.51%, with sensitivities of 100 GHz/RIU and 193 GHz/RIU, respectively. The second sensor also produces resonant peaks in the terahertz range, with absorption rates of 99.88% and 99.94% and sensitivities of 159 GHz/RIU and 226 GHz/RIU. After elucidating the physical mechanisms of both absorbers by analyzing the electric field and surface current distributions, we tested the dielectric constants of edible oils using the first sensor and evaluated the polarization insensitivity of the second sensor. These findings position the proposed sensors as versatile tools for biological detection and label-free detection even in trace amounts.