Thesis Title

A Sensor For DNA Hybridization Using Fluorescence and Electrical Impedance Detection

Date of Graduation

Fall 2006


Master of Science in Biology



Committee Chair

Paul Durham


biosensor, impedance, MEMS bridges, fluorescence, DNA hybridization

Subject Categories



To improve the current biodetection methods available, a proof of concept design for the biological component of an innovative nucleic acid biosensor, as well as characterization of biorecognition events by fluorescence and impedance has been established in this work. This basic DNA biosensor design involves the immobilization of thiolated single-stranded (ss) oligonucleotides (20-mer probe; 1.0 æM) on gold 7 mm half-moon transducer surfaces (with a 0.5 mm gap) to recognize its complementary (target) DNA sequence by hybridization. Electrical impedance is one method in which biorecognition events at the electrode surfaces can be obtained directly, without labeling, providing for rapid and simple analysis. This method has been used to optimize effects of the biosensor environment on the analytical signal, such as buffer volume, salt signal change when a complementary target was detected after only 20 minutes demonstrated the feasibility of using electrical impedance as a promising mode of non-complementary sequences providing the foundation for future, specific biosensors, such as micro electro-mechanical systems (MEMS) bridges, to be used in environmental diagnostics. MEMS bridge will enable multiple tests to be accomplished simultaneously, increasing the signal-to-noise ratio, and identifying a large range of microorganisms relevant to a given situation.


© Erin E. Sutton