Rapid and Inexpensive Method for Fabrication and Integration of Electrodes in Microfluidic Devices

Electrodes are essential components in a number of microfluidic devices for sensing and actuation. Current methods for electrode fabrication in microfluidic devices are mostly derived from the electronic industry and rely on expensive photolithography and sputtering processes. Here, in this paper, we demonstrate that a combination of xurography and cold lamination can be used to fabricate and integrate electrodes in microfluidic devices. This method is fast, inexpensive, direct and does not require any intermediate layer for pattern transfer. This method utilizes thin metal foils that are commercially available at low-cost and with a large variety of materials in the fabrication of electrode structures. We demonstrate that using xurography, electrode sizes down to 66 $\mu \text{m}$ and pitch sizes as small as 25 $\mu \text{m}$ can be obtained using these foils. After patterning, the electrodes were bonded to plastic films using pressure sensitive adhesives and integrated into microfluidic devices which were also fabricated using xurography approach combined with cold lamination. We demonstrate various applications of these electrodes as electrochemical sensors, as heaters for temperature control and as electrokinetic mixers. This simple method is low-cost and produces electrode structures that are ideally suited for application in microfluidic and lab-on-a-chip devices. [2019-0048]