Mediated Amperometric Biosensors

Abstract

A realistic estimate of the worldwide market for biosensors is around $360 million by 1996, $700 million by the year 2000, and then rising sharply.1 Probably the greatest impact from this burgeoning development will be felt in the field of medicine, particularly home diagnostic test kits. The current market for biosensors is dominated by mediated amperometric devices for glucose analysis. Undoubtedly, the introduction of the ExacTech glucose sensor, with annual sales of around $100 million, has helped to enhance the quality of life for many people suffering from diabetes. This is a rapid and reliable method for determining the concentration of blood glucose, carried out by means of a "user friendly" diagnostic tool. At the heart of this device lies a mediated biosensor. By adapting some of the methods of mass production used in the electronics industry, cheap disposable "one-shot" biosensors can be produced. Screen-printing (Figure 10.1) can be employed to produce a range of practical biosensor designs (Figure 10.2). In the near future the routine determination of a number of analytes may more readily be realized using mediated biosensor technology. A large European-wide research effort2 is currently underway to develop in vivo sensors for a range of analytes including glucose. For the glucose sensors the initial aim is to develop an implantable "hypoglycaemia alarm system"3 capable of providing an early warning system, alerting the wearer to serious fluctuations in blood glucose. This may be based on a simple needle-type sensor, capable of being implanted in the subcutaneous tissue of the patient.