Approach to quantitative detection of proteins with the biosensor based on imaging ellipsometry and spectroscopic ellipsometry

The biosensor based on imaging ellipsometry (BIE) is a practical technique to measure protein interactions such as the immobilization of biomolecules and the recognition between ligand and analyte. In this paper, to avoid the working condition optimization before each measurement, a fixed linear working condition for the silicon wafer chip is established at the angle of incidence of 75° with the fixed azimuths of the polarizer and the analyzer P = 90° and A = 45°. Further, a quantitative model is constructed to establish the standard curve between the ellipsometric signal and the protein concentration. As a result, this model is used to deduce the dissociation equilibrium constants of three relevant blood proteins as well as their antibodies. This work bridges the gap between the biochemical demand and BIE for sensing applications.