Biomedical Engineering Reference
In-Depth Information
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CHAPTER 1
Introduction to Biosensor
Technology
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1.1 Sensor Anatomy, Signaling and Properties
The notion of a sensor device is common knowledge to all. The range of these
structures in modern times is immense, ranging from simple physical
measurements such as temperature to complex devices that incorporate human
cells in their design. The number of applications is also numerous including
industrial processing, pharmaceutical analysis, automotive operation, military
technology and environmental signaling to name just a few areas of use. In
this section we introduce the basics of a special branch of sensor technology
that deals with the detection of chemicals, with relevance to the research in
neuroscience described later in the chapter. The emphasis is on devices, which
constitute the main structures employed in biosensor technology, rather than a
comprehensive review of the field.
Devices that detect and signal the presence of chemicals have evolved
through two different pathways, although the distinction between the two is
somewhat arbitrary. The structure is composed of a chemical recognition site
attached to a substrate surface which, in turn, is in close proximity and union
with a transducer. Such a system can be used to respond selectively to the
presence of chemicals we term the target or analyte, either in the gas or liquid
phase. The chemical recognition site is often referred to as the receptor or
probe. The technology relies on the ability of such a configuration to 'recognize'
chemicals through selective binding at the substrate surface of the device with
such surface presence being converted into an electrical signal via the particular
physics of a transducer. Chemical sensors are generally considered to involve
non-biological/biochemical probes in their design and the same is often
regarded to be the case for the analyte. A simple example is the well-known tin
