Abstract
Abstract Large-area and transparent all-dielectric metasurfaces sustaining photonic bound states in the continuum (BICs) provide a set of fundamental advantages for ultrasensitive biosensing. BICs bridge the gap of large effective mode volume with large experimental quality factor. Relying on the transduction mechanism of reactive sensing principle, herein, we first numerically study the potential of subwavelength confinement driven by topological decoupling from free space radiation for BIC-based biosensing. Then, we experimentally combine this capability with minimal and low-cost optical setup, applying the devised quasi-BIC resonator for PNA/DNA selective biosensing with real-time monitoring of the binding event. A sensitivity of 20 molecules per micron squared is achieved, i.e. ≃0.01 pg. Further enhancement can easily be envisaged, pointing out the possibility of single-molecule regime. This work aims at a precise and ultrasensitive approach for developing low-cost point-of-care tools suitable for routine disease prescreening analyses in laboratory, also adaptable to industrial production control.
Highlights
Advanced biomedical diagnostic technologies play a key role in improving healthcare and clinical diagnostic processes
We show that – despite the delocalized nature of the field in the transverse plane – our photonic crystal slabs (PhCS) is capable of a sensitivity of few-molecules per micron squared of sensing area even in realistic experimental settings in which the resonance quality factor becomes Q ∼ 102
Biosensors based on synthetic oligonucleotides such as peptide nucleic acids (PNAs) have provided an alternative to conventional platforms, pushing down the selectivity, and the sensitivity of nucleic acid assay [11]
Summary
Advanced biomedical diagnostic technologies play a key role in improving healthcare and clinical diagnostic processes. The possibility of engineering high quality factor cavities in microsphere resonators, ring resonators, photonic crystal resonators, waveguides, and circuits has led to interesting applications for perturbation-type measurements used in ultrasensitive (single molecule) biosensing In this direction, photonic crystal slabs (PhCS) and metasurfaces sustaining bound states in the continuum (BICs) were investigated [1], demonstrating the capability of highly sensitive trace-detection down to few-molecules regime [2,3,4,5,6,7,8], with potential electrical tunability [9].
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