The objective of this research is to apply micromachined silicon-based resonant
gravimetric sensors to the detection of gas-phase volatile organic compounds (VOCs). This
is done in two primary tasks: 1) the optimization and application of silicon disk resonators
to the detection of gas-phase VOCs, and 2) the development and application of a novel
gravimetric-capacitive multisensor platform for the detection of gas-phase VOCs.
In the rst task, the design and fabrication of a silicon-based disk resonator structure
utilizing an in-plane resonance mode is undertaken. The resonance characteristics of the
disk resonator are characterized and optimized. The optimized characteristics include the
resonator Q-factor as a function of geometric parameters, and the dynamic displacement
of the in-plane resonance mode. The Q-factors of the disk resonators range from 2600 to
4360 at atmosphere for disk silicon thicknesses from 7 µm to 18 µm, respectively.
The resonance frequency of the in-plane resonance mode ranges from 260 kHz up to 750 kHz.
The disk resonators are applied to the sensing of gas-phase VOCs using (poly)isobutylene
as a sensitive layer. Limits of detection for benzene, toluene and m-xylene vapors of 5.3
ppm, 1.2 ppm, and 0.6 ppm are respectively obtained. Finally, models for the limits of
detection and chemical sensitivity of the resonator structures are developed for the case of
the polymer layers used.
In the second task, a silicon-based resonator is combined with a capacitive structure
to produce a multisensor structure for the sensing of gas-phase VOCs. Fabrication of the
multisensor structure is undertaken, and the sensor is theoretically modeled. The baseline
capacitance of the capacitor component of the multisensor is estimated to be 170 fF. Finally,
initial VOC detection results for the capacitive aspect of the sensor are obtained.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/45780 |
| Date | 18 August 2011 |
| Creators | Truax, Stuart |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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