Detection and Coding of Chemical Signals: A Comparison Between Artificial and Biological Systems

Abstract

Although there has been no lack of ambitious researchers in the past 75 years, the problems put forward by the inventor of the telephone still await an answer. Hundreds of thousands of stimuli can be detected and discriminated by the nose. However, the basic principles of odour detection and coding are not yet well understood, and the development of artificial chemosensitive devices is still in its “kindershoes”. In this respect, the olfactory system is an exception among the sensory systems since there are excellent electrical analogues for all the other senses, above all the visual and auditory. Also, there are sophisticated methods of processing optically and acoustically recorded signals. On the other hand, there is an enormous need for intelligent chemosensitive devices: biochemical analyses in medicine and biology could be facilitated considerably. The control not only of food and beverage flavours, but also of poisonous and harmful substances in water and air would become feasible, if not easier. Although biological and artificial chemosensory systems show many obvious differences, there are also some principal and conspicuous similarities. E.g., some features of biological receptor cells such as a low stimulus selectivity resemble very much those of artificial sensors. Also, the second stage of both systems needs to process the stimuli in some ordered way which is simpler than the relatively complex stimulus response profiles of the primary receptor cells/sensors. Research in both fields should profit from cross-fertilization. In this article, an attempt is made to highlight the common and different features in biological and artificial chemosensory systems.