Date of Award

12-2005

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

Advisor

Mauricio Pereira da Cunha

Second Committee Member

Paul Millard

Third Committee Member

John Vetelino

Abstract

Waterborne pathogens have been connected with hemorrhagic colitis and hemolytic uremic syndrome, which may be characterized by diarrhea, kidney failure, and death. There is an urgent need for sensors capable of rapidly detecting dangerous microbes in food and water supplies to limit the exposure of human and animal populations. In this work, pure shear horizontal surface acoustic wave (SH SAW) biosensors have been designed, fabricated, and tested using langasite (LGS) Euler angles (0°, 22°, 90°). The delay lines implemented and tested exhibited reduced additional loss in liquids (~6 dB) due to the nature of the SH SAW mode. Resonator devices were used to confirm the temperature compensated behavior around room temperature of the LGS SH SAW orientation, (0°, 22°, 90°). Numerical comparisons between the referred orientation and the pseudo SAW along LiTa03 (0°, -54°, 0°), indicated equivalent sensitivity to viscosity and mass. LGS SH SAW delay lines were integrated with surface immobilized proteins. Successful detection of macromolecular protein monolayers was facilitated by a biosensor test setup specially designed and implemented in this work. In addition, the LGS SH SAW platform researched was effectively integrated with an anti-E. coli biological sensing layer, and applied to the detection of E. coli 0157:H7. The resulting biosensors produced significant, selective, and highly reproducible responses to the presence of E. coli. These results indicated excellent performance of the LGS SH SAW biosensor, with potential for a future commercialized device.

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