Ultrasensitive LSPR meta-devices for biochemical sensing

Abstract

Optical biosensing is a non-destructive, high sensitivity and low-cost method for quantitative detection of biocomponents. The reliable detection of abnormal cancer biomarkers at early stages of cancer is subtle and difficult to be observed. Thus, an extremely sensitive method is needed in early cancer detection. Traditional optical biosensing is based on the principle of detecting the variation of the refractive index, which limits its performance. In contrasts, biosensors based on localized surface plasma resonance (LSPR) detect the fingerprints of the analyte itself by observing and analyzing the interaction between the molecular vibrational modes and the surface plasma resonance. Thus, the sensitivity is enhanced. In this work, a metadevice with a tunable graphene layer integrated with silver grating microwires is designed to detect a kind of immunoglobulin used as the analyte. From its spectral responses, the fingerprint is extracted from the coupled transmission/reflection spectra. The target substance can be detected even at nanoscale concentrations.