Design and build an electronic nose using conducting polymers as transducers.

The goal of scientists at the University of Glasgow (Department of Electronics and Electrical Engineering, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, Scotland, U.K.) is to develop an electronic model nose that has some of the capabilities of the human olfactory system. Humans and other animals possess considerable discriminating power in the olfactory sensory pathways. A trained nose can easily distinguish between different complex odors for which there are minor differences in quantitative chemical composition. These include batches of perfumes, brands of coffee or blends of whisky. Most of the current electronic noses use chemically-specific sensors intended to detect a specific individual chemical.

The human olfactory system is believed, however, to use only a small number of chemical sensors to discriminate between very large numbers of gases, odors and mixtures. Researchers are using a similar approach. Their model nose uses a finite array of sensors, between 3 and 64. The sensors are independent, but each is sensitive to a very wide range of odors. Odors are identified by an adaptive pattern recognition analysis of the signals induced on the sensor array. The system module that handles the signal processing is a sophisticated parallel-processing system used to model the human olfactory system, as well as to provide an engineering solution to problems in olfaction.

The main applications for the prototype nose include online quality control of food and beverages. The model nose is also a prototype for another system being developed to detect general electrochemical signals in fluid and biological environments. There are three distinct efforts in this cross-disciplinary investigation. First, investigators are preparing and characterizing transducer materials (electro-active conducting polymers). They are studying the structure-activity relationships and the mode of action of odorants with the transducers. They also are fabricating and calibrating an array of microelectrode transducers that have been synthesized as a single integrated circuit.

A number of model noses have been successfully constructed and show considerable potential. Scientists are constructing a second-generation electronic nose with enhanced sensitivity and pattern recognition features. It is being applied to agriculture and veterinary science. Further information. J.R. Barker; phone: [phone]; fax: [phone].