Transducer mechanisms for optical biosensors. Part 2: Transducer design.

Optical fibre biosensors basically require two components, namely optical fibres, to enable remote measurements to be made, and immobilised reagents. The propagation of light along fibres is discussed and various effects causing attenuation and a fall in transmission efficiency, viz. coupling of light into the fibre and attenuation characteristics of the fibre itself, are considered. The modes of interaction of electromagnetic radiation with the immobilised reagent, viz. absorption alone, absorption followed by luminescence, reflection, or scattering, are discussed and followed by methods by which these effects can be utilised to provide an optically detectable signal. Practical sensor configurations are described and the associated optical instrumentation is outlined. Finally a brief overview is presented of the current state of the art of these sensors.