Ultrasensitive trace-analyte detection empowered by a quasi-BIC terahertz metasensor.

Area of Science:

• Terahertz (THz) spectroscopy
• Plasmonics
• Biosensing

Background:

• Ultrasensitive detection of trace biomarkers is vital for early disease diagnosis.
• Terahertz (THz) metasensors utilizing quasi-bound states in the continuum (quasi-BIC) offer high quality (Q) factors and strong field confinement for label-free biosensing.

Purpose of the Study:

• To propose and experimentally demonstrate a plasmonic metasensor for ultrasensitive trace-level biomarker detection.
• To achieve high refractive index sensitivity and a low detection limit for disease-related biomarkers.

Main Methods:

• Fabrication of an asymmetric circular split-ring resonator (CSR) enclosed by a square ring (SR) on a cyclo-olefin copolymer substrate.
• Excitation of a high-Q quasi-bound state in the continuum (quasi-BIC) resonance by breaking structural symmetry.
• Application of the metasensor for ultrasensitive detection of L-tyrosine.

Main Results:

• The metasensor demonstrated a high refractive index sensitivity of up to 200 GHz RIU⁻¹.
• Ultrasensitive detection of L-tyrosine was achieved with a detection limit as low as 0.33 μg mL⁻¹.
• The sensor design enables label-free detection of trace biomarkers.

Conclusions:

• The developed plasmonic metasensor offers a viable route for high-performance terahertz biosensing.
• This technology holds significant potential for point-of-care diagnostic applications.
• The high sensitivity and low detection limit are crucial for early disease diagnosis.