Abstract
An enzyme can be combined with an electrochemical sensor to produce an electrode that will measure the substrate for that enzyme. Such electrodes, known as enzyme electrodes, have enabled assay of many compounds of biochemical interest. However, they remain largely unexploited in medical measurement. This review gives the basic principles and describes electrodes used in biological solutions, together with an outline of the problems. The development of enzyme electrodes for continuous in vivo monitoring is emphasised.