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Detection of Heavy Metal Ions using Polymer Nanojunctions

Nongjian J. Tao*
Department of Electrical Engineering and Center for Solid State Electronics Research
Arizona State University, Tempe, Arizona 85287

Nanostructured materials are attractive for sensor applications because of their unique properties that promise high sensitivity and fast response time. We present two methods to fabricate metal/polyaniline/metal junctions and demonstrate a chemical sensor application of the junctions. In the first method, we fabricate metal electrodes separated with a few nm gap using a combined optical lithography and electrochemical techniques. We then bridge the gap with polyaniline to for a polymer nanojunction. In the second approach, the building blocks consist of a microelectrode array on a silicon chip and microfabricated metallic bars coated with a thin polyaniline layer. The individual bars suspended in solution are placed, with the help of a magnetic field, across the microelectrodes to form polyaniline junctions. The polyaniline layer is ~30 nm thick and modified with Gly-Gly-His oligopeptides. Strong binding of Cu2+ to the oligopeptide is converted into a conductance change of the junctions, allowing selective detection of trace amounts of Cu 2+ ions.

* Supported by EPA (R82962301).


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