Since living organisms are capable of sensing the presence of a variety of substances, they have been profitably used for developing devices, which will help in environment management, in health care and also in developing more efficient industries.

In designing a biosensor, an enzyme or an antibody or even microbial cells are associated with microchip devices, which are used for quantitative estimation of a substance. The subject is so important that an international congress, described as 'Biosensors 90' was held in Singapore during May 2-4, 1990. Second World Congress on Biosensors, i.e- 'Biosensors 92' was held in 1992.

A journal called 'Biosensors and Bioelectronics' is also being published to give the desired emphasis to this subject. A biosensor equipment consists of

(i) a biological sensing agent,

(ii) a device for collecting the product obtained from the interaction between the substrate and the biosensor, and

(iii) a device for measuring the quantity of this product, thus indirectly giving an estimate of the substrate.

In India, the Central Electrochemical Research Institute, Karaikudi has developed a glucose biosensor based on glucose oxidase enzyme. The enzyme is immobilized on an electrode surface acting as an electrocatalyst for oxidation of glucose.

The biosensor gives a reproducible electrical signal for glucose concentrations as low as 0.15 mM and works for several weeks with no appreciable degradation of enzyme activity.

Another related aspect is 'biomonitoring' or 'biological monitoring (BM)', which is defined as the "measurement and assessment of work place agents or their metabolites either in tissues, secreta, excreta or any combination of these systems" in occupationally exposed subjects (human beings).

While biomonitoring refers to uptake, distribution, biotransformation, accumulation and excretion of toxic agents, their biological effects in workers exposed to these agents are often described as 'Biological Effect Monitoring (BEM)'.