Master of Science in Electrical Engineering (MSEE)
Electrical and Computer Engineering
With the discovery of carbon nanotubes (CNTs), many applications have been implemented based on their unique electronic, mechanical, chemical and optoelectronic properties. One area of applications is in gas sensors for detecting, oxygen, flammable and toxic gases. In our work, the focus is on the fabrication of carbon nanotube (CNT) cantilever sensors for integration with CMOS readout chip which offer increased sensitivity. The higher surface-to-bulk ratio enhances the property and performance of the gas sensor by nanocantilevers. In this work, we present the detection method based on the change in capacitance of the single walled carbon nanotube (SWCNT) cantilever. Carbon nanotubes are capable of interacting with the gaseous species either directly or indirectly by using a polymer analyte coated on its surface. The capacitance variation technique of measuring cantilever deflection was used to measure the bending rate. The capacitance between the cantilever and the fixed electrode varies as a function of the magnitude of the bending of the cantilever which is in turn proportional to the concentration of the gas species in the surrounding environment. To measure the variation in the capacitance value, the CNT cantilever beam is considered as one of the electrodes of the capacitor and the metal film as the other. The air between the plates acts as the dielectric material. Simulations including both ANSYS for nanocantilevers and SPICE for CMOS readout chip and experimental results are presented in this research. Integration and packaging issues are also discussed in our research.
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Hsu, Jui-Ching, "Fabrication of single walled carbon nanotube (SW-CNT) cantilevers for chemical sensing" (2007). LSU Master's Theses. 3955.