High-performance differential surface plasmon resonance sensor using quadrant cell photodetector

We describe a simple, stable, and high-resolution surface plasmon resonance ~SPR! sensor using a quadrant cell photodetector. The sensor focuses a diode laser through a prism onto a gold film that is divided into two areas, one for reference and the other for sensing analyte. The angular shifts of the SPR generated in the two areas are detected with a quadrant cell photodetector. Because signals from the two areas are produced and detected with the same laser, optics, and photodetector, the difference in the SPR angular shifts eliminates errors due to thermal drift, mechanical noise, and laser fluctuations. It also removes the SPR angular shift due to the change in the refractive index of the bulk solution as an analyte solution is introduced into the sample cell each time, and thus gives an accurate detection of the specific adsorption of analyte. © 2003 American Institute of Physics. @DOI: 10.1063/1.1523649#