High Q-factor multiband terahertz metasurface biosensor for biomedical refractive index sensing: a numerical study

Area of Science:

• Terahertz (THz) technology
• Metasurface optics
• Biomedical sensing

Background:

• Terahertz (THz) metasurface absorbers offer high-Q resonances for biomedical sensing.
• Conventional single-band absorbers have limited reliability due to narrow frequency ranges.
• There is a need for advanced biosensors with enhanced sensitivity and stability.

Purpose of the Study:

• To introduce a polarization-independent, multiband metasurface absorber (MSA) for label-free terahertz biosensing.
• To demonstrate good angular stability for reliable detection.
• To enhance light-matter interactions for improved sensing performance.

Main Methods:

• Designed a compact metal-dielectric-metal (MDM) structure featuring a dual-metallic split-ring resonator and a ground plane.
• Investigated the absorber's performance for multiband absorption and spectral selectivity.
• Evaluated the sensor's sensitivity to refractive index variations for biological samples.

Main Results:

• Achieved six absorption peaks with >98% absorption at specific THz frequencies.
• Demonstrated a high Q-factor of 177 and narrow FWHM for spectral selectivity.
• Obtained high sensitivities (up to 8 THz/RIU) for detecting cancer- and malaria-related samples.

Conclusions:

• The proposed MSA is a simple, high-Q, multiband platform for THz biosensing.
• The design enhances light-matter interactions via electromagnetic field confinement.
• The platform is compatible with microfluidic integration for advanced biosensing applications.