Spectral-phase interference method for detecting biochemical reactions on a surface

A simple optical method is proposed for the direct detection of biochemical reactions on a surface, which is insensitive to variations in the radiation intensity and refractive index of a solution. The method is based on the detection of the spectrum of reflected or transmitted radiation modulated by the interference in a sensitive layer of a large thickness (several tens and hundreds of microns), which can be a microscope cover glass with a deposited receptor layer. A change in the phase of the interference pattern in this spectrum is used as an information signal about a change in the thickness of the sensitive layer caused by a biochemical reaction. The method was tested in studies of the reactions of binding and detachment of proteins in real time. The root-mean-square noise of the method expressed in the layer thickness is 3 pm.