Biosensors are analytical devices which are capable of providing either qualitative or quantitative results.
Biosensors combine the equisite selectivity of biology with the processing power of modern microelectronics and optoelectronics to offer powerful new analytical tools with major applications in medicine, environmental diagnostics and the food and processing industries.
Biosensors consist of bio-recognition systems, typically enzymes or binding proteins, such as antibodies, immobilised onto the surface of physico-chemical transducers. The term immunosensor is often used to describe biosensors which use antibodies as their biorecognition system. In addition to enzymes and antibodies, the biorecognition systems can also include nucleic acids, bacteria and single cell organisms and even whole tissues of higher organisms. Specific interactions between the target analyte and the complementary biorecognition layer produces a physico-chemical change which is detected and may be measured by the transducer. The transducer can take many forms depending upon the parameters being measured - electrochemical, optical, mass and thermal changes are the most common.