Laser micromachined wax-covered plastic paper as both sputter deposition shadow masks and deep-ultraviolet patterning masks for polymethylmethacrylate-based microfluidic systems

We report a technically innovative method of fabricating masks for both deep-ultraviolet (UV) patterning and metal sputtering on polymethylmethacrylate (PMMA) for microfluidic systems. We used a CO2 laser system to cut the required patterns on wax-covered plastic paper; the laser-patterned wax paper will either work as a mask for deep-UV patterning or as a mask for metal sputtering. A microfluidic device was also fabricated to demonstrate the feasibility of this method. The device has two layers: the first layer is a 1-mm thick PMMA substrate that was patterned by deep-UV exposure to create microchannels. The mask used in this process was the laser-cut wax paper. The second layer, also a 1-mm thick PMMA layer, was gold sputtered with patterned wax paper as the shadow mask. These two pieces of PMMA were then bonded to form microchannels with exposed electrodes. This process is a simple and rapid method for creating integrated microfluidic systems that do not require cleanroom facilities.