Surface plasmon differential ellipsometry of aqueous solutions for bio-chemical sensing

A differential surface plasmon ellipsometry technique is presented which allows the sensing of refractive index changes in aqueous solutions at the level of better than 5 x 10(-7) refractive index units. This level of sensitivity is comparable to the best currently available surface plasmon based sensing systems and can be implemented as a bio-chemical sensor. The technique has the additional advantage of being ideally suited to the development of a multi-channel array sensor.