Light-Tunable Hybrid Organic–Inorganic Nanostructured Layers for Virtual Sensor Arrays

Electronic nose (EN) is the most advanced technology for the classification and identification of complex gaseous mixtures. The idea is to use a small set of low-selective sensors instead of a huge number of specific ones. The response of such an array is a chemical image (CI) which is a mathematical (or graphic) representation of an analyte. The ability of an EN system to distinguish different mixtures is defined by its ability to produce a unique CI. The latter is defined and limited, first of all, by the sensor’s adsorption properties. We propose the approach to increase the versatility of low-selective sensor arrays by using virtual sensors. By “virtual sensor”, in this case we mean a sensor able to change its adsorption properties in conditions of illumination. Within this scenario, we were able to successfully distinguish between homologous alcohols (methyl, ethyl, and isopropyl) using organic–inorganic nanostructured sensitive layers based on ZnO nanoparticles and phthalocyanines (Pc). The performance of quartz crystal microbalance sensors with hybrid nanostructured organic–inorganic layers is increased in comparison with single-Pc ones. Using illumination allowed us to obtain additional responses which could be considered as virtual sensors. Both factors played the decisive role in the successful discrimination of the alcohols.