Electrode Fabrication in Plastic Microfluidic Devices for Hydrogen Detection

Walker, C., Xia, Z., Foster, Z., Lutz, B., and Fan, Z.H., "Electrode Fabrication in Plastic Microfluidic Devices for Hydrogen Detection," Electroanalysis, Vol. 20, No 6, pp 663-670, March 2008. (Abstract)

Abstract: We report fabrication of microelectrodes by airbrushing, a technique primarily used for commercial arts. Similar to screen-printing, airbrushing enables conductive inks to be patterned onto a thin film. The film with ink electrodes is then laminated with a plastic substrate with microchannels to form a microfluidic device. The device is designed to implement enzyme-catalyzed electrochemical detection for sensing hydrogen. We found that airbrushed electrodes perform in a similar fashion with screen-printed electrodes. The cyclic voltammetric peak separation for ferrocyanide is 0.34 V, suggesting a nonreversible redox behavior as observed for the screen-printed ink electrodes. A linear calibration curve is obtained for 2 to 20 mM ferrocyanide in a flow using chronoamperometry, which is the method we previously exploited for demonstrating enzyme-catalyzed electrochemical detection in a large flow cell. The process parameters of airbrushing, including ink concentration, have been characterized. The benefits of fabricating electrodes by airbrushing include a simpler process, lower cost, and requiring less skill. This technique is especially useful in situations where a commercial screen-printing machine is inaccessible.