October 2007

Document Type


Degree Name



Dept. of Biomedical Engineering


Oregon Health & Science University


Advancements in the micro sensor and integrated chip technologies have led to the integration of sensors and the quantifying electronics in a single package. Various lab-on-chip (LOC) techniques have been developed and are usually geared towards the bio-tech industry, dealing frequently with analysis of target molecules in liquid medium. Similar integrated technology has also evolved for the detection of gaseous analytes and is commonly known as electronic nose or e-nose. It would be of great advantage if multiple targets in both liquid and gaseous mediums could be identified and quantified by a single device. This would also serve as a common platform for the development of new detection strategies. In this dissertation, I have developed a sensor-array chip hybrid for rapid parallel detection of multiple organic or inorganic target molecules in either gas or liquid mediums. The developed system is based on measuring minute changes in capacitances for detection. The sensors in the designed sensor-array chip hybrid are capacitive sensors, micro fabricated on top of a pre-designed CMOS chip with circuitry to measure small changes in capacitance. The capacitor sensors were built using the well advanced technique of focused ion beam (FIB) micromachining and microforming. In this thesis I also present multiple circuit techniques that can detect femto farad changes in sensor capacitance. I have validated these circuits by simulation and post fabrication electrical testing. I have also evaluated the applications of this system in multidisciplinary research including: 1) Detection and measurement of organophosphate neurotoxins 2) Air quality monitoring - detection of low concentrations of carbon monoxide gas 3) Aid in the study of early detection of stroke




OGI School of Science and Engineering



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