Transparent Conductive Materials (TCMs) - 2018
Plenary Speaker - Metal Oxide Nanowires gas sensors array for food quality control and safety

The complex food system is changing continuously. Processing of food has developed over the time ensuring easily accessible, more nutritious, safe and affordable food [1]. Maintenance of human health is the main target in order to minimizing risks and maximizing the benefits. Nevertheless, even if the food quality control systems are in the forefront of technology development, the major cause of hospitalization in developed countries is related to food poisoning. World Health Organization reports as statistics that 1 in 10 people fall ill every year from eating contaminated food and 420 000 people die each year as a result [2].

Current chemical, physical and microbiological techniques employed for the quality control process in the food production chain are extremely reliable but in the major of cases require the use of high-trained lab staff, costly equipment and are time consuming. In this scenario, more time-effective techniques are required in order to avoid economic losses and to preserve the consumer’s health. New and innovative technologies have been developed thanks to the progress in nanotechnology. Chemical sensors based on metal oxides semiconductors with the nanowires shapes are proved to be the most promising as gas sensors thanks to low-cost fabrication processes, simple preparation and operation and easily applicable to the food control. In this presentation, we are reporting the synthesis of MOX NWs using different technologies such as thermal evaporation, thermal oxidation and anodization.

MOX nanowire gas sensors are incorporated as an array in a portable device, Small Sensor System (S3), able to assess the quality and the safety of food through the analysis of VOCs. In food field, S3 applications range from the evaluation of the identity of a specific food, in order to avoid fraud, to the monitoring of cooking and storage processes in ovens and fridges. In the first case, S3 has been successfully applied for different food matrices: for instance, it has been used for the quality control of Parmigiano Reggiano cheese [3] and the presence of chemical and organic contaminants in potable water [4].

The versatility of this system is due to its ability to connect to the internet: S3 has its own user-friendly Web App developed by NASYS Srl. Users can set up sessions of measurements, see all the measures that have been done divided in different projects, plot the graphs of sensors responses, do multivariate statistical analysis as Principal Component Analysis (PCA) and train artificial neural networks (ANNs) for classification purposes. .