Investigation of Airbrushing for Fabricating Microelectrodes in Microfluidic Devices

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.