Generating Bio-Analogous Recognition of Artificial Materials – Sensors and Electronic Noses for Odours
Chemical sensing is a key application of bio-inspired smart materials. Artificial nanostructured layers mimicking biorecognition are synthetically accessible e.g. by imprinting techniques or affinity material nanoparticles. Hence, for detecting extremely malodorous organic thiols (butane/octance thiol), we designed molybdenum disulphide nanoparticles. In contrast to soft metals (e.g. gold) they interact with the SH-group fully reversibly leading to one of the first real QCM sensors for these compounds. Rationally varying the surface of the recognition material allows for optimizing the interaction properties. Electrolyzed gold e.g. shows sensor effects being about an order of magnitude higher than screen printed electrodes. Furthermore, molecular imprinting leads to highly selective cavities in polymers (polyurethanes, -styrenes, -acrylates) for detecting odorous compounds, e.g. aliphatic alcohols, ethyl acetate and limonene. With these materials, we designed an electronic nose for monitoring plant degradation processes based on a six-electrode QCM (quartz crystal microbalance) array. With a variety of degrading materials (grass, fruit, conifers), it determines the above analytes down to some ppm directly on-line. The concentration data can be extracted from the E-nose frequency shifts by Neural Networks and validated by GC-MS.
Pietro VINCENZINI and Salvatore GRAZIANI
P. A. Lieberzeit et al., "Generating Bio-Analogous Recognition of Artificial Materials – Sensors and Electronic Noses for Odours", Advances in Science and Technology, Vol. 58, pp. 103-107, 2008