An Introduction to the Industrial Applications of Biosensors

Abstract

What is a biosensor? Many authors have attempted to define this potentially ubiquitous device but occasionally one is still faced with the problem of explaining, to those unfamiliar with the term, how a biosensor is different from the numerous biochemical laboratory techniques currently used to define biological activity. ‘Is not a spectrophotometer a biosensor?’ is often the first question asked. Essentially biosensors differ from existing techniques in three useful and fundamental ways.

• (1) In that there is an intimate contact of the biological material (whether it be whole cells, organelles, antibodies or enzymes) with a transducer which converts the biological signal into a quantifiable electrical signal.

• (2) In its functional size. The ‘sensing’ portion of the biosensor is generally small and this allows small test sample size, minimum interference with existing processes following implantation, and access to difficult and possibly dangerous environments, without interrupting process flow.

• (3) In that biological material can be selected to suit the industrial needs and operate at various levels of specificity. It may be highly specific; may be specific to a narrow band of compounds; or may exhibit spectrum specificity. A theoretical illustration of this gradation in specificity would be a sensor sensitive to a single antibiotic (for example, gentamycin), or all aminoglycosides or all antibiotics. This flexibility in choice of biological material allows the user to ‘tailor’ the biosensor to the industrial process.