On-chip terahertz metasensor for quantitative multi-component biomolecular identification.

Terahertz (THz) metasensors are promising platforms for quantitative biomolecular fingerprint identification in physical, chemical, and biomedical applications. However, conventional free-space THz configurations are limited by their large size and susceptibility to external disturbances, hindering the development of compact and portable devices. Recent advances in on-chip THz metasensors harness miniaturization, yet existing implementations primarily focus on qualitative detection of single molecule types, lacking the capability for quantitative, multi-component analysis. Here, we present an on-chip THz metasensor fabricated on a self-supporting 20 μm-thick lithium niobate (LN) wafer, capable of both identification and quantification of multi-component biomolecular mixtures. By patterning a periodic metasurface array directly onto the LN substrate, our design integrates THz generation, molecular interaction, and signal detection into a single 4 mm × 8 mm chip, achieving a five-order-of-magnitude reduction in the size of the THz functional module relative to conventional THz time-domain spectroscopy systems. Leveraging broadband surface-localized THz waves from the metasurface, this chip accurately identifies and quantifies mixtures of four biomolecules with an error below 3.60%. This work advances THz fingerprint sensing by offering a robust and scalable platform as a portable solution for quantitative multi-component biomolecular analysis.