Page 186 - Analytical Electrochemistry 2d Ed - Jospeh Wang

Analytical Electrochemistry, Second Edition. Joseph Wang
Copyright # 2000 Wiley-VCH
ISBNs: 0-471-28272-3 (Hardback); 0-471-22823-0 (Electronic)

CHAPTER 6

ELECTROCHEMICAL SENSORS

A chemical sensor is a small device that can be used for direct measurement of the
analyte in the sample matrix. Ideally, such a device is capable of responding
continuously and reversibly and does not perturb the sample. By combining the
sample handling and measurement steps, sensors eliminate the need for sample
collection and preparation. Chemical sensors consist of a transduction element
covered with a chemical or biological recognition layer. This layer interacts with the
target analyte and the chemical changes resulting from this interaction are translated
by the transduction element into electrical signals.
The development of chemical sensors is currently one of the most active areas of
analytical research. Electrochemical sensors represent an important subclass of
chemical sensors in which an electrode is used as the transduction element. Such
devices hold a leading position among sensors presently available, have reached the
commercial stage, and have found a vast range of important applications in the ®elds
of clinical, industrial, environmental, and agricultural analyses. The ®eld of sensors
is interdisciplinary and future advances are likely to derive from progress in several
disciplines. Research into electrochemical sensors is proceeding in a number of
directions, as described in the following sections. The ®rst group of electrochemical
sensors, the potentiometric ion-selective electrodes (based on ``ionic receptors''), has
been described in Chapter 5.

6-1 ELECTROCHEMICAL BIOSENSORS

Electrochemical biosensors combine the analytical power of electrochemical tech-
niques with the speci®city of biological recognition processes. The aim is to

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