L-Cysteine Polymorph Coatings for THz Sensing Metasurfaces

TL;DR

This paper presents a novel asymmetric all-metallic metasurface for THz biosensing, demonstrating high sensitivity and potential for detecting biomolecules like L-Cysteine with different crystallographic structures.

Contribution

It introduces a new asymmetric metasurface design that enhances THz biosensing capabilities for different L-Cysteine crystal forms, with detailed analysis of concentration effects.

Findings

Frequency shifts correlate with analyte concentration.

Achieved a Q-factor of 37 for the metasurface.

Sensitivity of 1.430 THz ml/g for detection.

Abstract

The electromagnetic response of metasurfaces can be intentionally engineered by carefully designing their unit cells. Narrowband metasurfaces, characterized by high quality factors, can serve as an efficient platform for biosensing in optical to THz regimes, to explore new structural forms of biomolecules, further elevating the capabilities of THz sensing technologies. In this study, an all-metallic metasurface featuring structural asymmetry is proposed to analyze L-Cysteine with orthorhombic and monoclinic crystallographic structures. The influence of the concentration of L-Cysteine in the monoclinic phase on the THz response of the metasurface was performed using a drop-casting method. Our findings reveal a noticeable frequency shift as analyte concentration raises, underscoring the potential for high sensitivity in detecting biomolecules. Thus, this research demonstrates that asymmetric THz metasurfaces offer rather promising detection capabilities at lower THz frequencies between two crystallographic structures of L Cysteine, with a Q-factor of 37, and a sensitivity of 1.430 THz ml/g. We believe that our results can be of great value to the development of biosensors for improved material characterization at low frequencies.