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

Chemical and biochemical sensors have a broad spectrum of applications including 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 designed, which typically use several sensors, all of which operate with one of the various possible signal transduction principles, The latter concern changes in resistance, impedance, current, capacitance, work function, mass, temperature, 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/mass spectrometer couplings, GC/MS). The main problem results from the fact that the individual sensors usually show drift, are not sensitive enough, and detect only certain classes of molecules. (C) 2000 Elsevier Science S.A. All rights reserved.