Towards a truly biomimetic olfactory microsystem: an artificial olfactory mucosa

Today, the capability of the human olfactory system is still, in many ways, superior to that of the electronic nose. Although electronic noses are often compared with their biological counterpart, they neither mimic its neural architecture nor achieve its discriminating performance. Experimental studies on the mammalian olfactory system suggest that the nasal cavity, comprising of the mucous layer and the olfactory epithelium, performs a degree of chromatographic separation of complex mixtures. Thus receptor cells distributed beneath the mucous layer provide both spatial and temporal chemosensory information. Here we report on the development of an artificial olfactory microsystem that replicates this basic structure. This contains an integrated channel to emulate the nasal cavity and coated with a polymer to mimic the partitioning mucous layer, which is positioned directly over a sensor array. Our system employs an 80 element chemoresistive microsensor array with carbon black/polymer odour-sensitive films combined with a microfluidic package fabricated by micro-stereolithography. Results show that this biomimetic system generates both spatial and temporal odorant signals, with a temporal chemical retention period of up to 170 s. Data analysis has revealed improvements in its ability to discriminate between two simple odours and a set of complex odours. We believe such emulation of the olfactory system can lead to improved odour discrimination within the field of electronic noses.