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Ag/AgCl Microelectrodes with Improved Stability for Microfluidics



Brian J. Polk, Anna Stelzenmuller, Geraldine I. Mijares, William A. MacCrehan, Michael Gaitan


A method for fabricating Ag/AgCl planar microelectrodes for microfluidic applications is presented. Microreference electrodes enable accurate measurements with miniaturized chemical sensors but such electrodes often exhibit very limited useable lifetimes. Our goal is to reliably construct Ag/AgCl microelectrodes with improved potential stability and which are compatible with surface mounted microfluidic channels. Electrodes with geometric surface areas greater than or equal to 100 square micrometers were fabricated individually and in array format by electroplating silver, greater than 1000 nm thickness, onto photolithographically patterned thin-film metal electrodes. The top surface of the electroplated silver was chemically oxidized to silver chloride to form Ag/AgCl microreference electrodes. Characterization results showed that Ag/AgCl microelectrodes produced by the fabrication method exhibit increased stability compared with many devices previously reported. Electrochemical impedance spectroscopy allowed device specific parameters to be extracted from an equivalent circuit model and were used to describe the performance of the microelectrodes in a microfluidic channel. Thus, stable Ag/AgCl microelectrodes produced with a combination of photolithographic techniques and electroplating demonstrated utility for analysis within microfluidic systems.
Sensors and Actuators B, Chemical


Ag/AgCl, microelectrode, microfluidics, Microreference electrode, reference electrode


Polk, B. , Stelzenmuller, A. , Mijares, G. , MacCrehan, W. and Gaitan, M. (2006), Ag/AgCl Microelectrodes with Improved Stability for Microfluidics, Sensors and Actuators B, Chemical (Accessed May 19, 2024)


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Created March 29, 2006, Updated October 12, 2021