The bound state in the continuum in flexible terahertz metasurfaces enabled sensitive biosensing

Area of Science:

• Metamaterials and Nanophotonics
• Terahertz Technology
• Flexible Electronics

Background:

• Electromagnetic wave manipulation is crucial for advanced photonic devices.
• Flexible metasurfaces offer new possibilities for tunable electromagnetic responses.
• Bound states in the continuum (BIC) provide sharp resonances for enhanced light-matter interactions.

Purpose of the Study:

• To experimentally demonstrate a flexible metasurface capable of supporting bound states in the continuum (BIC) in the terahertz regime.
• To investigate the tunability and mechanical robustness of the flexible BIC metasurface.
• To showcase the sensing capabilities of the device.

Main Methods:

• Fabrication of a flexible metasurface using toroidal dipole resonant units on a polyimide substrate.
• Experimental analysis of terahertz Friedrich-Wintgen BIC resonance characteristics.
• Investigation of BIC resonance under varying mechanical bending conditions.
• Demonstration of sensing application using Fetal Bovine Serum.

Main Results:

• Successful demonstration of a flexible metasurface supporting terahertz BIC resonance.
• Tunable resonance characteristics by adjusting coupling unit parameters.
• The metasurface exhibited decent mechanical robustness under bending.
• Achieved a minimum detectable concentration of 0.007 mg mL^-1 for Fetal Bovine Serum sensing.

Conclusions:

• The flexible BIC metasurface effectively manipulates terahertz waves.
• The device's mechanical flexibility and BIC properties enable multifunctional applications.
• Potential for realizing novel, adaptable photonic devices in the terahertz spectrum.