Sensor responses in a single component medium are shown in Fig.2
and Fig. 3. They illustrate the sensitivity of different types of non-specific
chemical sensors to inorganic and organic substances. The sensor responses of
carefully developed and selected materials can be very reproducible (typically + 1-3 mV,
while the scale of measured effects is often 20, 50 even 100 mV and more) and really long
lasting (typical life time for a solid sensor is several years, of an organic polymer one - up
to 1 year). Such sensors are put together in sensor sets combining up to 10-40 different sensors.
In the multi component media (e.g. many food stuffs and beverages) the response of such
sensors comprised into an array is usually not linear any more, but it is still reproducible
and the differences between samples are usually very significant.
Sensor array of the electronic tongue mainly consists of two types of sensors - chalcogenide
glass ones and polymer-based sensors.
The system architecture is intrinsically open, thus other sensors and sensor devices can be
incorporated and even other methods can be put together with the electronic tongue to produce
wider complementary information about an analyte.