Biosensors combine the 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.What is a Biosensor? (1)The term biosensor has been applied to devices either (1) used to monitor living systems, or (2) incorporating biotic elements. The consensus, however, is that the term should be reserved for use in the context of a sensor incorporating a biological element such as an enzyme, antibody, nucleic acid, microorganism or cell. For the purposes of this tutorial, a biosensor will be defined as:Analytical devices incoporating a biological material or a biomimic (e.g. tissue, microorganisms, organelles, cell receptors, enzymes, antibodies, nucleic acids etc.), intimately associated with or integrated within a physicochemical transducer or transducing microsystem, which may be optical, electrochemical, thermometric, piezoelectric or magnetic.The usual aim of a biosensor is to produce either discrete or continuous digital electronicsignals which are proportional to a single analyte or a related group of analytes.Where are Biosensors Being Used?Biosensors are finding use in increasingly broader ranges of application. The following list describes some of the current applications. Clinical diagnosis and biomedicine Farm, garden and veterinary analysis Process control: fermentation control and analysis Food and drink production and analysis Microbiology: bacterial and viral analysis Pharmaceutical and drug analysis Industrial effluent control Pollution control and monitoring Mining, industrial and toxic gases Military applicationsHow Can Biosensors Benefit Bioprocesses?SpecificityLike other bioanalytical methods (such as immunosassays and enzyme assays), biosensors use a biologically derived compound as the sensing element. The advantage of biological sensing elements is their remarkable ability to distinguish between the analyte of interest and similar substances. With biosensors, it is possible to measure specific analytes with great accuracy.SpeedOne characteristic of biosensors that distinguishes them from other bioanalytical methods is that the analyte tracers or catalytic products can be directly and instantaneously measured. There is no need to wait for results from lengthy procedures carried out in centralised laboratories.SimplicityThe uniqueness of a...