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Tutorials Micro-Optic and Fiber Optic Sensors Terahertz Sensing Noise Harvesting Chemical and Gas Sensing Industrial Tomography Silicon Piezoresistive Stress Sensors Miniaturised Space Payloads Integrated Gas Sensors Sensors as Communication Channels Nanophotonic Sensors Biopolymer Detection Integrated Radar Sensors Ultrasonics |
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One of today challenging topics in the gas sensor field is the fabrication of integrated sensing chips (SChips) containing chemical sensors together with electronic devices and circuits. Downscaling today cumbersome sensor systems to millimeter-sized monolithic SChips is particularly attractive for the development of non-intrusive, single chip wireless sensor network nodes, to be deployed into rooms, vehicles or even applied to cloths, as a part of personal area networks. A number of meso- and nano-strucutured materials (metal-oxides, polymers, porous silicon, carbon nanotubes) have been proposed as gas sensor devices, basically resistor or capacitor made up by the sensing material itself, to be integrated into SChips. Nonethless, the bottleneck of SChip fabrication still is the actual compatibility between today sensor technologies and integrated circuit (IC) fabrication processes. Solid-state devices (SSD), like diodes and transistors, are building-blocks of any integrated electronic circuit. Smart modification of SSD by means of meso- or nanostructured materials would lead to advanced solid-state gas sensors (SSGSs), such as sensing diodes or transistors, with higher electronic performances, with respect to resistor/capacitor sensors. In SSGSs, adsorption/desorption processes occurring in the sensing material are translated into changes of the electrical characteristics of the SSD (current or voltage), which becomes therefore sensitive. Advantages of such an approach, with respect other approaches reported in the literature, are: intrinsic compatibility of SSD with IC industrial processes and, in turn, more straigforward integration of the consequent SSGS; well-known electrical and physical behavior of the SSD and, in turn, viable design and modeling of the consequent SSGS; increased flexibility and performances of fabricated SSGSs and, in turn, optimization of the SSGS behavior; no need for electrical contact fabrication upon the sensing material, which is just used as a sensing layer to modify the SSD electrical properties, and, in turn, strighforward postprocessing integration of the sensing material itself with commercial IC processes. In this tutorial, 1) smart modification of SSDs (diodes and transistors) by mesostructured porous silicon (PS) layers, aimed to the fabrication of integrated SSGSs, will be presented; 2) experimental characterization and theoretical modeling of SSGSs will be given and discussed; 3) integration of SSGSs by using commercial CMOS-based IC processes will be presented and detailed; finally, 4) fabrication and experimental characterization of SSGS-based SChips will be demonstrated and discussed. Biography Giuseppe Barillaro received his Laurea degree in Electronic Engineering and his Ph.D. degree in Information Engineering from the University of Pisa in 1998 and 2002, respectively. From November 2002 to November 2005 he was a post-doctoral research fellow at the Information Engineering Department of the University of Pisa, where since December 2005 he is permanent researcher. He is currently Lecturer Fellow, teaching "Electronic Instrumentation" (Electronic Engineering) and "Bioelectronics" (Biomedical Engineering) at the Faculty of Engineering, University of Pisa. Concerning the research activity, he is currently working in the Microelectronic Technology and Microsystems Lab (Information Engineering Department, University of Pisa), where since 2006 he has been leading a research group. Giuseppe Barillaro has achieved in his career significant skills in the design, modelling, fabrication and characterization of new materials and devices as well as in their integration on the same silicon chip to get complex microsytems. In last ten years, he has carried out research activity on different topics (solid-state gas sensors, porous silicon, silicon micromachining, photonic crystals, silicon and metal nanomachining), and with different applications (environment, optics, space, microelectronics, biomedics), always significantly going beyond the state-of-the-art. His scientific production, almost fully produced as main author, includes 1 International Patent, more than 30 papers on international peer reviewed journals, 36 papers on proceedings of international conferences and 19 papers on proceedings of national meetings. Giuseppe Barillaro is currently national coordinator of project "Photonic Crystal Optofluidic Microsystems for Biosensing" funded by the Italian Ministry for the University and the Research, within the framework of PRIN - 2008/2010, and co-investigator of the project "Integrated microsystem for transdermal drug delivery" funded by Fondazione Cassa di Risparmio di Pisa - 2007/2009. |
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