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Stabilizing Planar Micro-Machined Micro-Reference Electrodes

Sigma Xi Post-Doc Poster Session

February 19, 2004

Brian J. Polk,? Geraldine Mijares,? William MacCrehan,? Michael Gaitan?

We are developing CMOS compatible methods for fabricating thin-film Ag/AgCl micro-reference electrodes. Micro-reference electrodes are needed to make accurate voltammetric chemical and biochemical measurements with high spatial resolution. A few target applications for these electrodes include 1) electrochemical detection of DNA separations, 2) potentiometric chemical sensing in microfluidic systems, and 3) electrochemical analysis of single living cells. A major problem with many micro-sized quasi-reference electrodes is maintaining a constant potential over a long period of time. By combining micromachining with chemical and electrochemical surface treatments we have successfully stabilized the potential of thin-film Ag/AgCl electrodes to within 2 mV over a period of at least four days of continuous measurement. We present here the fabrication and surface treatment protocols as well as potentiometric characterization for a range of electrode sizes.

? NIST, EEEL, Semiconductor Electronics Division

? NIST, CSTL, Analytical Chemistry Division

Contact Name: Brian J. Polk

Division: Semiconductor Electronics (812)

Laboratory: EEEL

Room: B310

Building: Technology, 225

Mail Stop: 8120

Telephone: 301-975-6347

FAX: 301-948-4081


Sigma Xi member?: No

Category: Chemistry