Discrimination of aliphatic homologues and isomers using trap and GC enhanced SAW based electronic noses

We present a new electronic nose system for discrimination of chemically related analytes and complex mixtures. The system employs a miniaturized array of eight polymer coated surface acoustic wave (SAW) sensors and a small preconcentration unit ('trap'). A GC column with atmospheric pressure air as the carrier gas is implemented as a separation unit. Design considerations are made with particular emphasis on the necessities arising from the interplay between sensors, coatings, trap, column, gas fluidics, and pattern recognition software. The system was tested against alkane homologues and hexane isomers. It successfully identifies n-hexane from other alkanes, even at very small concentrations (<1 ppm).