Metal oxide in forms of nanowires are interesting for their peculiar morphology and their exceptional crystalline features. The first assuring a high surface to volume ratio necessary to maximize surface related properties such as the ones governing chemical sensing transduction principles. The latter guaranteeing stable crystalline and therefore electrical properties over long term operation, i.e. a required quality for an industrial application of any kind of sensor in real environments.
Furthermore other peculiarities make them much more interesting than their thin or thick film counterpart, for example lateral dimensions comparable to the surface charge region, the possible modulation of the operating temperature to select the proper surface reactions, the self heated device option, catalyst can be deposited over the surface to enhance or reduce specific reactions and moreover their potential integration in field-effect transistors configuration to add a gate potential for a further opportunity to change sensitivity and selectivity.
After the first method proposed for the preparation of metal oxide in forms of nanobelts [Science, 2001 291,1947] plenty of literature was devoted to different experimental techniques that may lead to the formation of these quasi one dimensional structures. At the beginning the research was focusing of the vapour phase methods that were producing, with cheap instrumentation, high quality nanostructures in terms of crystallinity and stoichiometry.
We have thoroughly studied the deposition using evaporation and condensation from powder in controlled environment using different experimental set up. Tin oxide was preferred with respect to other oxides thanks to its well known chemical sensing properties and to the easy preparation condition, but also copper and zinc oxide were studied.
Metal oxide nanowires were integrated in functional devices for chemical sensing and then tested towards a wide range of chemicals, including odorous molecules such as ammonia, hydrogen sulfide. To further gain selectivity, innovative gas-sensor architectures, based on surface ionization mechanism and magnetic field activation, have been investigated and will be presented.
Author’s Short Biography
Prof. Giorgio Sberveglieri is a full professor in experimental physics in University of Brescia since 1996. His research has spanned a wide spectrum of activities ranging from thin films to nanostructured materials exhibiting remarkable sensing properties in the field of gas sensors, biosensors and solar cells. He is the founder and the director of the Sensor Laboratory, CNR–IDASC and Brescia University (http://sensor.ing.unibs.it), which is dedicated to tailoring material structure in micro and nanoscale to optimize their response, developing functional metal oxide layers and exploring new application fields. During 35 years of scientific activity, he published more than 315 papers in international journals and he is highly cited with h-index = 42. He has given more than 250 presentations at international congresses including numerous invited and plenary talks, and acted as the General Chairman/Chairman in several Conferences on Materials Science and on Sensors. He serves as evaluator of European Union in the area of Nanoscience - Nanomaterials and ICT, Associate Editor of IEEE Sensor Journal, Chair of the Steering Committee of the IMCS series Conference, referee of many international journals, and coordinator of 7FP EU Project S3.