Loss-driven miniaturized bound state in continuum biosensing system

TL;DR

This paper introduces a miniaturized, high-sensitivity BIC biosensing system utilizing a Q-switched mechanism in a 3D metasurface, achieving superior detection limits and potential for home cancer diagnostics.

Contribution

It presents a novel Q-switched sensing approach in a 3D BIC metasurface that enhances sensitivity and enables mass production for practical biosensing applications.

Findings

Peak intensity sensitivity of 928 %/RIU achieved

Detection limit of 10E-5 refractive index units

Able to detect 129 aM extracellular vesicles

Abstract

Optical metasurface has brought a revolution in label-free molecular sensing, attracting extensive attention. Currently, such sensing approaches are being designed to respond to peak wavelengths with a higher Q factor in the visible and near-infrared regions.Nevertheless, a higher Q factor that enhances light confinement will inevitably deteriorate the wavelength sensitivity and complicate the sensing system. We propose a Q-switched sensing mechanism, which enables the real part of the refractive index to effectively perturbate the damping loss of the oscillator, resulting in a boost of peak intensity.Consequently, a higher Q factor in Q-switched sensor can further enhance the peak sensitivity while remaining compatible with broadband light sources, simultaneously meeting the requirements of high performance and a compact system.This is achieved in a unique 3D bound-state-in-continuum (BIC) metasurface which can be mass-produced by wafer-scale aluminum-nanoimprinting technology and provides a peak intensity sensitivity up to 928 %/RIU.Therefore, a miniaturized BIC biosensing system is realized, with a limit of detection to 10E-5 refractive index units and 129 aM extracellular vesicles in clinical lung cancer diagnosis, both of which are magnitudes lower than those of current state-of-the-art biosensors. It further demonstrates significant potential for home cancer self-testing equipment for post-operative follow-up. This Q-switched sensing mechanism offers a new perspective for the commercialization of advanced and practical BIC optical biosensing systems in real-setting scenarios.