Surface plasmon resonance bio- and chemical sensors with phase-polarisation contrast

Phase-polarisation contrast (PPC) method for the enhancement of the contras t of Surface Plasmon Resonance (SPR) information pattern is proposed and re alised. The method consists in the optimisation of the optical scheme for S PR dip visualisation, that makes use of the behaviours of light phase and p olarisation under SPR. A converging light beam with a variable polarisation ellipticity is used for surface plasmon excitation, while the reflected be am is analysed by a phase compensator and an analyser. Using the PPC method , we have observed the enhancement of the SPR pattern contrast by more than one order of magnitude in comparison with traditional SPR schemes. This al lowed us to increase significantly the accuracy of SPR shift measurements i n bio- and chemical sensing and to reduce restrictions on allowable dispers ion of parameters of SPR-supporting metal films and binding layers immobili sed on them. In addition, the PPC method can provide a gain in sensitivity. (C) 1999 Elsevier Science S.A. All rights reserved.