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

Email: brian.polk@nist.gov

Sigma Xi member?: No

Category: Chemistry