Artificial Perceptual Sensors - Artificial Human Sensors: Science and Applications - page 154

Figure 6.17. The strategy of sensor design is exemplified by the concept of an electronic

tongue.

organisation path of the design there are some decisions that have to be consid-
ered. As an example, the strategy in a sensor design has to be defined and fully
understood to achieve proper knowledge about the operational principle used.
The chosen strategy for an electronic tongue device may be as shown in Fig. 6.17.
An illustration of the sensor design of concern is demonstrated, and the
available options are hopefully known. The chosen strategy is built upon a ba-
sic electronic tongue concept applying the technique of voltammetry. Further, the
sensor responses are adapted toward the application of sensing water contami-
nation that, in this example, is illustrated by eventually identifying contaminated
compounds added in the water. The fine-tuning of the chosen types of sensors is
most likely not optimised and further assumption about the system performance
is capable to substantially increase the capability to fit specific sensing applications
is left to the reader to evaluate. The conceptual strategy is shown in Fig. 6.17.
Voltammetry is a technique of electroanalytical principles in which informa-
tion about the analyte is derived from the measurement of an applied current,
Christian (2004). A potential is applied at an electrode and the current flow-
ing through the electrodes, typically working-, auxiliary- and reference-electrodes
(Fig. 6.18). An electrochemical redox reaction occurs at the electrodes contact
surface with the liquid of interest, which give rise to a measurable “fingerprint”,
that normally can be detected by identifying the specific concentration of a cer-
tain property. The sensor output is typically measured as a function of the applied
potential, or simply the time. As the electrochemical method of potentiometry
is also a common method used to design electronic tongue systems it ought to
be mentioned. The contrast to voltammetry is that potentiometry uses a static
technique, which provide the sensor system output with relative potentials that
are measured. Details of different chemical methodologies can be found in Skoog
(2004).