A device and method of detecting surface plasmon resonance for sensing
molecules or conformational changes in molecules with high resolution and
fast response time is disclosed. Light from a light source (14) is focused
through a prism onto a metal thin film (15) on which sample molecules to
be detected are adsorbed. The total internal reflection of the
laser/incident light is collected with a differential position or
intensity sensitive photo-detecting device instead of a single cell or an
array of photo-detectors (12) that are widely used in previous works. The
ratio of the differential signal to the sum signal of the differential
position or intensity sensitive photo-detecting device (12) provides an
accurate measurement of the shift in the surface plasmon resonance angle
caused by the adsorption of molecules onto the metal films (15) or by
conformational changes in the adsorbed molecules. The present invention
requires no numerical fitting to determine the resonant angle and the
setup is compact and immune to background light, The methods and sensors
of this invention can be used in numerous biological, biochemical, and
chemical applications such as measuring subtle conformational changes in
molecules and electron transfer reactions can be studied.
