Degree Type

Dissertation

Date of Award

2002

Degree Name

Doctor of Philosophy

Department

Electrical and Computer Engineering

First Advisor

Robert J. Weber

Abstract

Tapered-width cantilevers are proposed to give designers more design space in obtaining lower pull-in voltage and higher capacitance change for a cantilever with relatively short length and moderate area. Several types of the width taper functions have been investigated in this research. Based on the analytical form of the pull-in voltage for a simple cantilever, we have obtained empirical forms of the pull-in voltages for tapered-width cantilevers. These formulae can be the basis of the pull-in voltage synthesis by geometry control of a cantilever and might be helpful for integrated cantilever sensor systems in which only low actuating voltage is available. The measured pull-in voltages of cantilevers together with these formulae were used to extract the Young's modulus of the material (polysilicon), which is 175 GPa with a standard deviation 40 GPa.;For applications of micro-mechanical structures, on-chip circuitry is preferred to do the signal conditioning to avoid parasitics of bonding pads/wires, which is usually comparable to or larger than the motional induced capacitance change if interest. Unfortunately, not every micro-machining process is compatible with the fabrication processes for integrated circuits; instead they are usually very customized for their particular applications. In this project, we have investigated RF measurement techniques for the characterization of microstructures and a direct-conversion circuit based on the electromechanical amplitude modulation/demodulation scheme has been built for possible off-chip readout circuitry applications. A direct measurement of input voltage and through-current was used to obtain the input admittances of devices under test, from which the equivalent circuits can be extracted.

DOI

https://doi.org/10.31274/rtd-180813-12227

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Chieh-Hsiao Wang

Language

en

Proquest ID

AAI3143534

File Format

application/pdf

File Size

145 pages

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