Biosensing Platform – Ultrasensitive, Label-Free

Researchers have combined the physics of dielectric metasurfaces and hyperspectral imaging to create an ultrasensitive, label-free biosensing platform. The platform can detect and analyze samples at spatial concentrations of less than three molecules per square micron. It could ultimately enable compact portable diagnostics for personalized medicine. It could also offer a route to high-throughput, high-resolution optical characterization of single-atom-thick, 2-D materials such as graphene, an essential requirement for advancing the technical development of those much-ballyhooed materials.

As cells or biomolecules bind to the nanostructures, they change the local refractive index by a tiny amount, leading to sharp changes in the peak wavelength of the surface plasmon resonance. Those wavelength changes can be read to track the biological agent’s presence, concentration, and growth under study.

The dielectric biosensing platform relies on a different resonance, enabled by so-called bound states in the continuum (BICs). Originally a concept from quantum mechanics, BICs are confined waves that remain localized within a continuous spectrum of radiating waves.

Combining high-Q resonant dielectric metasurfaces and data acquisition (high-throughput, imaging-based) amounts to a superior and versatile sensing platform. Further explorations—leveraging alternative materials, other dimensions such as incident-light polarization, and machine learning—could still expand the system’s flexibility, potentially enabling a field-deployable high-throughput single-molecule detector for biomedical applications.

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