New ways of chemical sensing via fluctuation spectroscopy
Additional Document Info
Intensive research has been going on during the past several years to use chemical and biological sensor elements to develop systems known as electronic noses and electronic tongues. They consist of several sensor elements and a pattern recognition unit comprising data acquisition and usually a neural network software. The neural network, or a similar pattern recognition tool, is necessary due to the non-linear character of the sensor system, which "learns" to interpret data during a calibration process. There are several important practical issues, such as ways to decrease the number of necessary sensors, ascertaining sufficient sensitivity, obtaining reproducibility, diminishing the need for frequent calibration, and establishing the most suitable pattern recognition technique. This paper addresses the need for multiple sensors and demonstrates that measurements of conductivity fluctuations in a sensor can lower the required number of sensors to, in principle, only one. Moreover, we shall show that a new kind of electronic nose, a sampling-and-hold electronic nose can be realized in this way.