Ultrahigh-sensitivity label-free optical biosensor based on a silicon nanowire rectangular optical waveguide for lung cancer detection

Abstract

An ultrahigh-sensitivity optical biosensor is proposed and analyzed for early detection of lung cancer based on a silicon nanowire rectangular optical waveguide (SNROW). Parametric optimization is performed to get high surface sensitivity with compactness of the device for label-free biosensing by two-dimensional vectorial finite element methods. The proposed device is very effective in early detection of lung cancer based on the examination of variation in thickness of the functionalization layer due to binding with target biomarkers. Waveguide surface sensitivity is calculated by measuring the change in index of refraction per unit adlayer thickness variation. The waveguide surface sensitivity is obtained at 0.167 nm−1 with a cross-sectional area of 1255 nm×670 nm for the SNROW-based biosensor.