Mask-free laser lithography for rapid and low-cost microfluidic device fabrication

Copyright © 2018 American Chemical Society. Microfluidics has become recognized as a powerful platform technology associated with a constantly increasing array of applications across the life sciences. This surge of interest over recent years has led to an increased demand for microfluidic chips, resulting in more time being spent in the cleanroom fabricating devices using soft lithography - a slow and expensive process that requires extensive materials, training and significant engineering resources. This bottleneck limits platform complexity as a byproduct of lengthy delays between device iterations and affects the time spent developing the final application. To address this problem, we report a new, rapid, and economical approach to microfluidic device fabrication using dry resist films to laminate laser cut sheets of acrylic. We term our method laser lithography and show that our technique can be used to engineer 200 μm width channels for assembling droplet generators capable of generating monodisperse water droplets in oil and micromixers designed to sustain chemical reactions. Our devices offer high transparency, negligible device to device variation, and low X-ray background scattering, demonstrating their suitability for real-time X-ray-based characterization applications. Our approach also requires minimal materials and apparatus, is cleanroom free, and at a cost of around $1.00 per chip could significantly democratize device fabrication, thereby increasing the interdisciplinary accessibility of microfluidics.