The optimal substrate choice for effective biosensors based on THz metasurfaces

Area of Science:

• Optoelectronics and Photonics
• Biosensing Technology
• Materials Science

Background:

• Terahertz (THz) metasurfaces are rapidly advancing, but fundamental research on their components is crucial.
• The dielectric substrate is a critical factor influencing metasurface performance across spectral ranges.
• Previous studies often fixed substrate types or used simplified metal models, limiting optimization.

Purpose of the Study:

• To investigate the impact of substrate selection on the sensitivity of metallic terahertz metasurface sensors.
• To analyze design principles including plasmon resonances and Fano resonances in transmission mode metasurfaces.
• To provide guidance for designing high-Q, low-loss terahertz metasurface biosensors.

Main Methods:

• Simulated metallic terahertz metasurfaces on various substrates (Ge, Si, SiO₂, TPX) using COMSOL Multiphysics.
• Experimentally validated simulation results by detecting varying concentrations of bovine serum albumin (BSA).
• Systematically examined real-metal modeling and substrate effects on Q-factor and sensing performance.

Main Results:

• Low-refractive-index substrates significantly enhance sensor sensitivity for transmission mode terahertz metasurfaces.
• Real-metal modeling and substrate choice critically influence the Q-factor and overall sensing performance.
• Demonstrated improved sensor performance compared to studies with fixed substrates or perfect electric conductor models.

Conclusions:

• Low-refractive-index substrates are the preferred choice for optimizing terahertz metasurface biosensor sensitivity.
• This research offers valuable insights for designing next-generation high-sensitivity biosensors.
• Findings pave the way for new prospects in advanced terahertz sensing applications.