Patent ID: 7368294

Claim:
A method of optical detection of binding of at least one material component to a substance due to a biological, chemical or physical interaction, said method comprising the steps of: (a) providing a sensor layer formed by a solid optical material, said sensor layer having two boundary surfaces separated from each other by a distance of more than 10 μm; (b) immobilizing said substance on at least one of said boundary surfaces; (c) contacting a gaseous sample or liquid sample, which contains said material component, with the at least one of said boundary surfaces so that interaction between the material component and the substance takes place; (d) irradiating said sensor layer by a beam of polychromatic light, comprising a spectrum with a plurality of wavelengths, for which said solid optical material is at least partially transparent, wherein the beam is sufficiently collimated and a variation of an optical thickness of the sensor layer is such that a difference of optical paths inside the sensor layer for different light rays of said beam does not exceed a fourth of the smallest wavelength in the spectrum of said polychromatic light, wherein the polychromatic light has a coherence length that is less than double the distance between the boundary surfaces of the sensor layer; (e) recording a modulated spectrum, containing interference maximums and minimums due to interference either between light beams reflected from said boundary surfaces with said substance and said material component or between light beams transmitted through said boundary surfaces with said substance and said material component; (f) tracking a spectral shift of the interference maximums and minimums of said modulated spectrum that is due to a change of optical thickness between said boundary surfaces with said substance because of binding with said material component; and (g) deriving from said spectral shift the parameters of binding of said material component to said substance.