We are using mainly (but not exclusively) potentiometric chemical sensors for
solution analysis. This is the widest, the most well-known and profoundly developed
and studied class of chemical sensors. Many of earlier available sensors (conventionally
called ion-selective electrodes) for solution analysis were insufficiently selective.
For this reason their application for analytical purposes has been significantly restricted.
On the other hand it is possible to develop a very wide range of materials, which
can display reproducible sensitivity to multiple substances in liquids. The idea of
the electronic tongue approach is to develop and employ the sensors with broad
sensitivity - cross-sensitivity to as many species in solutions as possible. On the basis
of our knowledge and experience we can prepare and apply unique sensors displaying
response to inorganic and organic substances, to ionic and non-ionic species, to the
groups of chemically similar substances, etc. These sensors are stable and robust;
their response is highly reproducible.
Fig. 1 shows the difference between selective and non-selective,
cross-sensitive sensors in the analysis of a complex media. With selective sensors
(left part) one can determine only few substances in a complex liquid. With non-specific,
poorly selective sensors (right part) it is possible to obtain a number of different
patterns which combination can give an adequate description of the multi component
analyte. For this purpose they are combined into a sensor array (sensor set).