Reusable terahertz metasurface microfluidic sensor with enhanced sensitivity for trace liquid analysis.

This study presents a reusable, high-sensitivity terahertz (THz) metasurface sensor integrated with a 4.1 µm ultra-thin microfluidic channel to address the critical challenges of low sensitivity and trace solution detection in conventional THz sensing platforms. Through comprehensive numerical simulations and experimental validation, we demonstrate a sensor achieving 0.565 THz/RIU sensitivity for minute analyte volumes (0.4 µL), representing a 2.58-to-5.64-fold enhancement over conventional THz metasurface structures. The measured resonance frequency shifts (Δf) for 0.4 µL of ethanol, methanol, glycerin, and water were 363 GHz, 400 GHz, 475 GHz, and 623 GHz, respectively, with excellent agreement between experimental and simulation results. This work significantly advances THz sensing technology by enabling high-sensitivity detection of both polar and non-polar trace analytes, with important implications for biochemical sensing and aqueous solution analysis.