From electronic to bioelectronic olfaction, or: from artificial "moses" toreal noses

Chemical and biochemical sensors have a broad spectrum of applications incl uding in particular environmental monitoring, process and medical control, and quality analysis. Since individual sensors usually cannot fulfill such complex tasks, commercial instruments (''electronic noses") have been desig ned, which typically use several sensors, all of which operate with one of the various possible signal transduction principles, The latter concern cha nges in resistance, impedance, current, capacitance, work function, mass, t emperature, or optical properties. However, in most applications even such sensor arrays are still insufficient in their performance if compared with established instruments of analytical chemistry (like gas chromatograph/mas s spectrometer couplings, GC/MS). The main problem results from the fact th at the individual sensors usually show drift, are not sensitive enough, and detect only certain classes of molecules. (C) 2000 Elsevier Science S.A. A ll rights reserved.