Date of Award

Spring 2005

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Micro and Nanoscale Systems

First Advisor

Hai-Feng Ji

Abstract

Microcantilevers provide an ideal platform for biosensors. The micron-sized transducer brings several advantages, such as high sensitivity, small sample quantity for analysis, portability, implantable sensor devices, and the ability to be mass produced and integrated into standard microelectronic processing technologies like complementary metal oxide seminconductors (CMOS).

The objective of this research is to investigate and develop modification methods of microcanitlevers for biosensing applications.

Two microcantilever modification methods were investigated. They are self-assembly monolayer method and layer-by-layer method. A fundamental procedure for modification of microcantilevers using the layer-by-layer approach was developed for the first time in this research. These modification methods for microcantilevers provide practical ways for immobilization of recognition specifics, such as enzymes and antibodies, on the surface of the microcantilever. The modifications allow for detection of corresponding targets.

In this research, the following results have been obtained: (1) Development of a glucose sensor using microcantilever with layer-by-layer nano assembly containing glucose oxidas. The sensor has a response time in the range of seconds. (2) Development of a hydrogen peroxides sensor using the microcantilever with layer-by-layer nano assembly containing hydrogen peroxides. The detection limit for this sensor is 10−9M. (3) Development of a sensor for detection of biowarfare agents. For the measurement of Tularemia, this sensor reached the detection limit of 103 organism/ml. (4) Development of a sensor for detection of chemical warfare agents with sensitivity of 10−7M for organophosphates.

The results obtained from this research have demonstrated that the microcantilever-based biosensors can be developed for detection of various biomoleules or monitoring different processes. The glucose sensor developed in this research has great potential to be used as implantable glucose sensor for continuous blood glucose monitoring, which is critical in diabetes care. And the sensor for detection of biowarfare agents could be used for homeland security, which is one of the most important issues of the nation.

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