Review of chemical sensors for physiological measurement.

The continuous measurement of chemical species is important for physiological and biochemical research and for critical care medicine. Chemical sensors are being developed for the measurement of a wide range of analytes, especially gases, vapours, ions, catabolites, drugs and hormones. The mechanical form of these sensors may be adapted for use in single cells, tissue fluid and blood vessels, on the skin surface, in the respiratory and gastrointestinal systems. Optical and electro-chemical principles are now used widely for sensor design, and advances in electronic fabrication methods and in optical fibres, sources, and detectors, have been important.