Practical application of wax printing in microfluidics

Microfluidic devices manage precise flow using minuscule fluid volumes for applications in DNA evaluation, micro-chemical reactions, and many others. Microfluidic systems simultaneously reduce material cost and device size. One method for creating microfluidic devices applies wax patterns onto filter paper, creating hydrophobic barriers and hydrophilic flow chambers. This research applied, optimized, and validated facets of existing physical models for fluid flow through porous media. The research explored the general process of creating a microfluidic design using wax and paper, optimizing paper membrane selection, processing temperature, and soak time to improve functionality and precision in the design. A series of experiments were conducted and analyzed using barrier testing and MATLAB image processing measurement techniques of pre- and postmanufacture test samples. Utilizing scaling factors based upon the Washburn equation for porous flow, functional barrier widths of 200 micrometers were produced. Results were compared with the theoretical proportionalities postulated by Whiteside et. al. Results further yielded a simple, reproducible process to create barriers and predict spreading and minimum functional barrier width for a given type of Whatman paper. The outcome of this work will be used to improve the design of a novel point-of-care sensor device being developed at UPEI.