Real-time biomolecular interaction analysis using the resonant mirror sensor

The resonant mirror is a planar waveguide optical sensor that uses frustrated total internal reflection to couple light in and out of the waveguide layer. As a biosensor, the device exploits the highly selective binding interactions between pairs of biomolecules such as enzyme–substrate, antibody–antigen, hormone–receptor and DNA–DNA (DNA = deoxyribonucleic acid). As many of these species have no absorption bands at convenient (visible) wavelengths, refractive index sensing is employed to detect the displacement of water by the higher refractive index analyte as it interacts with its immobilized binding partner. The sensor chip construction is relatively simple, using techniques developed for the production of anti-reflection coatings and interference filters. Preliminary experimental results are presented from two instrumental configurations using a single type of sensor chip. Both types of instrument use linear or two-dimensional charge coupled device (CCD) arrays as detectors, thus avoiding the use of moving parts in the instrumentation.