Biomedical Engineering Reference
In-Depth Information
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Figure 1.8
Molecularly imprinted polymer. Schematic of proves where poly-
merization is conducted around protein, followed by removal to produce a
recognitive cavity.
technologies, the 'right' polymer can be found by interrogation ready
for further development.
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1.4 Device Transduction of Biochemical Interactions
A number of sensor strategies have been developed over the years for the
purpose of transducing a variety of biochemical events into an electrical signal.
Here we review concisely the three main categories—electrochemical, acoustic
wave and optical approaches. It should be noted that this compendium is not
exhaustive; for example, there are pyroelectric and other devices available.
However, the areas specified above dwarf all other sensors in terms of numbers
of applications.
1.4.1 Electrochemical Systems
There are a number of different approaches possible from the world of
electrochemistry, which involves the transfer of electrons at a solid-liquid
interface. A pre´ cis of these is presented in Table 1.2. A particularly useful
feature of many of these techniques is that they can be combined 'naturally'
with various forms of integrated electronic circuitry. Indeed the necessary
chemistry can be imposed directly on the surface of such an electronic device
(see later).
The literature displays a number of reviews of this transduction which can be
accessed by the reader for more detail.
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Here we deal with a concise
compendium of key characteristics, systems and devices.
1.4.1.1 Potentiometry
The defining principle of sensors based on potentiometry is that an indicating
electrode for the analyte of interest is incorporated in an electrochemical cell
(with reference electrode) for which minimal or no current is passed. In this
