Wafer-scale titanium anodic bonding for microfluidic applications

We report the development of an anodic bonding process that allows, for the first time, high-strength joining of bulk titanium and glass substrates at the wafer-scale, without need for interlayers or adhesives. We demonstrate that uniform, full-wafer bonding can be achieved at temperatures as low as 250 °C and that failure during burst pressure testing occurs via crack propagation through the glass, rather than the titanium/glass interface, thus demonstrating the robustness of the bonding. Moreover, using optimized bonding conditions, we demonstrate the fabrication of rudimentary titanium/glass-based microfluidic devices at the wafer-scale, and their leak-free operation under pressure-driven flow. Finally, we also demonstrate the monolithic integration of nanoporous titanium dioxide within such devices, thus illustrating the promise embodied in titanium anodic bonding for future realization of robust microfluidic devices for photocatalysis applications.