High Quality-Factor All-Dielectric Metacavity for Label-Free Biosensing

Area of Science:

• Nanophotonics
• Biosensing
• Optical Engineering

Background:

• Achieving high sensitivity and quality-factor in photonic biosensors is critical but challenging due to conflicting requirements for optical confinement and light-biomolecule interaction.
• Existing designs often struggle to simultaneously optimize these essential sensing parameters.

Purpose of the Study:

• To develop a novel biosensor configuration that enhances both optical field confinement and light-biomolecule interactions.
• To create a high-performance, low-cost, and scalable biosensor for sensitive biomolecule detection.

Main Methods:

• Embedding a nanophotonic metasurface within a micro vertical cavity to form a meta-channel (metacavity) biosensor.
• Utilizing the analyte solution as the cavity medium to maximize light-analyte interactions.
• Employing anodic aluminum oxide template technique and wafer bonding for large-scale, low-cost fabrication.

Main Results:

• The metacavity biosensor demonstrated a high quality-factor (up to 4140) and bulk refractometric sensitivity (450 nm/RIU).
• An unprecedented figure-of-merit of 1670 RIU⁻¹ was achieved.
• High surface sensitivity was observed, with a detection limit of 119 viral copies/mL for label-free SARS-CoV-2 pseudovirus sensing.

Conclusions:

• The developed metacavity biosensor effectively addresses the simultaneous need for strong optical confinement and enhanced light-analyte interactions.
• This approach offers remarkable performance in both bulk and surface sensing applications.
• The fabrication method enables scalable and cost-effective production of advanced photonic biosensors.