Studies on a low-cost gas sensor array useful to detect onion postharvest diseases in storage

A gas sensor array, consisting of seven Metal Oxide Semiconductor (MOS) sensors that are sensitive to a wide range of organic volatile compounds was developed to detect rotten onions during storage. These MOS sensors were enclosed in a specially designed Teflon chamber equipped with a gas delivery system to pump volatiles from the onion samples into the chamber. The electronic circuit mainly comprised a microcontroller, non-volatile memory chip, and trickle-charge real time clock chip, serial communication chip, and parallel LCD panel. User preferences are communicated with the on-board microcontroller through a graphical user interface developed using LabVIEW. The developed gas sensor array was characterized and the discrimination potential was tested by exposing it to three different concentrations of acetone (ketone), acetonitrile (nitrile), ethyl acetate (ester), and ethanol (alcohol). The gas sensor array could differentiate the four chemicals of same concentrations and different concentrations within the chemical with significant difference. Experiment results also showed that the system was able to discriminate two concentrations (196 and 1964 ppm) of methlypropyl sulfide and two concentrations (145 and 1452 ppm) of 2-nonanone, two key volatile compounds emitted by rotten onions. As a proof of concept, the gas sensor array was able to achieve 89% correct classification of sour skin infected onions. The customized low-cost gas sensor array could be a useful tool to detect onion postharvest diseases in storage. Source A Customized Metal Oxide Semiconductor-Based Gas Sensor Array for Onion Quality Evaluation: System Development and Characterization Tharun Konduru 1, Glen C. Rains 2 and Changying Li 1,* 1, College of Engineering, University of Georgia, 200 D.W. Brooks Dr., Athens, GA 30602, USA; E-Mail: kondurutharun@gmail.com 2, Department of Entomology, University of Georgia, 2360 Rainwater Road, Tifton, GA 31793, USA; E-Mail: grains@uga.eduSensors 2015, 15(1),?1252-1273 The picture shows a top view of the electronic circuit designed for gas sensor array (figure 5 of the paper)Key wordsCebolla onion ui ??? ?? cepo oignon ???????? ????? cipolla cebula cebola ??? so?an ???? Zwiebel Poscosecha postcosecha postharvest na-oes ?? ??? ?????? ?? post-r?colte ???? ?? ????????? na-oogst post-raccolta Obr?bka po p?s-colheita ?????????????? hasat sonras? Ernte ?????????????? ???? ??????????? postcollita poskliz?ov? ?? ?? ? nakon branja pozberov? obdelovanje zemlje po post-colleita ????? ????? pascapanen ?il?onn postharvest ???? p?c ra?as derliaus apdirbimas po lepas tuai ?? ?? ?????? post-recoltare ?????? ????? ????????????????? ??????????? ??????????????? sau thu ho?ch ??????????????? zangemva kwenkathi yokuvuna