Electrochemically controlled optical waveguide sensors

Optical techniques are at the forefront of modern analytical methods due to their inherent high specificity. From the point of view of sensor technology, the transfer of chemical information into a measurable signal is of utmost importance. In this respect, planar optical waveguides show great promise for realising novel chemical and biological sensors which use evanescent fields to probe specifically sensitised films on the waveguide surface. Such sensors may detect changes in the refractive index of films using, for example, surface plasmon resonance (SPR) [1], light emission from the binding of proteins labelled with fluorophores [2], or the change in absorption spectrum of a film caused by a chemical reaction [3]. The use of photolithography in integrated optics technology allows mass production of complex multisensors on small and robust substrates. Electrochemical methods allow electrical resetting of reactions, or improved sensitivity through phase-sensitive detection.