Metamaterial absorber integrated microfluidic terahertz sensors

TLDR

Spatial overlap between electromagnetic fields and analytes is essential for strong light‑matter interaction, yet sensitivity is usually limited by the localized near‑field of plasmonic antennas or the decayed resonant mode outside cavities. The authors propose and demonstrate a novel metamaterial absorber integrated microfluidic (MAIM) sensor operating in the terahertz range. By tuning the electromagnetic parameters of the MDM structure, the absorber confines fields within the hollow dielectric channel, greatly enhancing analyte–THz interaction. The MAIM sensor achieves a predicted sensitivity of 3.5 THz/RIU, with experimental measurements at ~1 THz matching simulations, and the concept is extendable to other frequency ranges for matter detection and biosensing. An illustrative image accompanies the paper.

Abstract

Abstract Spatial overlap between the electromagnetic fields and the analytes is a key factor for strong light‐matter interaction leading to high sensitivity for label‐free refractive index sensing. Usually, the overlap and therefore the sensitivity are limited by either the localized near field of plasmonic antennas or the decayed resonant mode outside the cavity applied to monitor the refractive index variation. In this paper, by constructing a metal microstructure array‐dielectric‐metal (MDM) structure, a novel metamaterial absorber integrated microfluidic (MAIM) sensor is proposed and demonstrated in terahertz (THz) range, where the dielectric layer of the MDM structure is hollow and acts as the microfluidic channel. Tuning the electromagnetic parameters of metamaterial absorber, greatly confined electromagnetic fields can be obtained in the channel resulting in significantly enhanced interaction between the analytes and the THz wave. A high sensitivity of 3.5 THz/RIU is predicted. The experimental results of devices working around 1 THz agree with the simulation ones well. The proposed idea to integrate metamaterial and microfluid with a large light‐matter interaction can be extended to other frequency regions and has promising applications in matter detection and biosensing. image