Terahertz Biosensor Engineering Based on Quasi-BIC Metasurface with Ultrasensitive Detection

Area of Science:

• Photonics and Metamaterials
• Biosensing Technology
• Terahertz Spectroscopy

Background:

• Terahertz (THz) sensors are valuable for non-destructive, contact-free analysis of biochemical samples.
• Quasi-bound state in the continuum (QBIC) metasurfaces (MSs) offer ultrahigh sensitivity for biosensing applications.
• QBIC-based MSs are reliable platforms for terahertz radiation-based biomaterial sensors.

Purpose of the Study:

• To design and investigate a structure-engineered THz MS based on a "double C" array for enhanced biosensing.
• To optimize the Q-factor of the QBIC device by engineering an asymmetry parameter (α).
• To demonstrate the sensor's capability for detecting trace biomolecules, specifically arginine.

Main Methods:

• Design of a "double C" array THz MS with an introduced asymmetry parameter (α).
• Theoretical calculations using coupling equations to model THz transmission spectra.
• Numerical simulations to obtain THz transmission spectra.
• Experimental testing using an MS with α = 0.44 to detect varying concentrations of arginine molecules.

Main Results:

• Theoretical calculations accurately reproduced simulated THz transmission spectra.
• Experimental detection of arginine molecules showed significant transmission changes near QBIC resonant frequencies.
• The amplitude change in response to arginine was 16 times higher compared to classical dipole resonance.
• A direct limit of detection for arginine molecules as low as 0.36 ng/mL was achieved.

Conclusions:

• The engineered THz QBIC MS provides a sensitive platform for detecting trace molecules.
• The asymmetry parameter (α) effectively optimizes the Q-factor for improved sensing performance.
• This approach enables rapid, accurate, and non-destructive sensing of biomaterials with potential applications in diagnostics.