Lattice Slot Waveguide for Terahertz Microfluidics Biomedical Trace Analysis

ABSTRACT Electromagnetic metasurface integrated microfluidic chips enable a real‐time, label‐free platform for terahertz trace analysis of volume‐limited biomedical samples with suppressed water absorption noise. However, conventional metal‐insulator‐metal (MIM) metasurface resonators exhibit inherently limited Q‐factor and sensitivity due to radiative leakage through open side boundaries. Here, a lattice slot waveguide based on MIM configuration is designed to effectively confine energy within the microfluidic channel and mitigate radiative loss. This trapped mode achieves enhanced sensitivity and Q‐factor through synergistic excitation of surface lattice resonance and guided mode resonance under propagation constant matching conditions. Leveraging this platform, an anisotropic detection strategy incorporating a patterned lattice structure is devised to achieve simultaneous polarization multiplexed responses, exhibiting a figure of merit of 135 in both polarizations. Experimental validation demonstrates a limit of detection of 625 pmol mL ⁻¹ and a Q‐factor of 189 for this polarization multiplexing microfluidic platform. This work offers a unique avenue for enhanced accuracy and efficiency in terahertz biomedical trace analyzing via multidimensional sensing capabilities.