Surface plasmon resonance interferometry for micro-array biosensing

Interferometry that detects the phase of a beam reflected under surface plasmon resonance (SPR) has been developed for bio and chemical sensing. The conditions have been found, under which the phase reveals abrupt jumps in response to a minute increase in the effective thickness of a receptor layer that binds analyte particles on the sensor surface. This forms the basis for biosensing with sensitivity much higher as compared to traditional SPR sensors. Besides, SPR interferometry (SPRI) provides spatial resolution at the micron scale. The enhanced sensitivity attributed to the phase jump and interferometric imaging of variations of the phase over the surface are demonstrated, which open up new avenues for micro-array biosensing. (C) 2000 Elsevier Science S.A. All rights reserved.