Flat Plasmonic Biosensor with an On-Chip Metagrating-Integrated Laser.

Area of Science:

• Optics and Photonics
• Biotechnology
• Materials Science

Background:

• Metasurfaces offer compact optical solutions, replacing bulky traditional components.
• Surface Plasmon Resonance (SPR) is a powerful technique for label-free biomolecular detection.
• Conventional SPR systems are often benchtop-bound and require complex optical setups.

Purpose of the Study:

• To develop a miniaturized, on-chip SPR biosensor using metasurfaces.
• To enable label-free biomolecular analysis in a chip-scale format.
• To demonstrate the feasibility of integrating metaoptics with semiconductor lasers for SPR.

Main Methods:

• Fabrication of a metasurface integrated with semiconductor lasers.
• Emission of collimated light into a glass substrate for angle-resolved SPR measurements.
• Demonstration of bulk refractive index sensitivity and multiplexed microRNA detection.

Main Results:

• Achieved a bulk refractive index sensitivity of 4.9 × 10^-6 RIU.
• Demonstrated limit of detection for microRNA at 0.1 nM (direct sensing) and 0.02 nM (with antibody amplification).
• Eliminated the need for conventional optics in the SPR setup.

Conclusions:

• The metasurface-based SPR biosensor is a miniaturized, chip-scale platform for label-free biomolecular analysis.
• The platform shows high sensitivity and potential for multiplexed detection of low-molecular-weight analytes.
• Scalable fabrication and low-cost components suggest broad applicability and mass production potential for diverse sensing modalities.