Optical bio-molecular sensor based on surface plasmon resonance

A new optical bio-molecular sensor was developed for bio-molecular sensing based on light-excited surface plasmon resonance (SPR). Thickness of bio-molecule films absorbed onto a gold film is measured by the resonance condition of the surface plasmon on the sensing mental surface. The resonance condition is given by thickness of bio-molecule films faced on the mental. The developed sensor can be compact and simple, because of the absence of mechanical moving parts, by using a wedge of laser beam to obtain incident angle scanning and multi-channel angular light intensity detection with a charge coupled device (CCD). The sensor using Kretschmann configuration includes three parts: an optical measuring unit, a power source of laser, and a microcomputer used as data collection and handling. The adsorption of ferritin from phosphate buffered saline (PBS) onto a gold film has been examined using the sensor. Application of the sensor allows elucidation of the surface layer thickness of dry ferritin on gold. Experiment results suggest less than monolayer coverage of ferritin on gold.