Fabrication Method for Paper Microfluidics Utilizing 3D Printing and PDMS Stamps

Paper microfluidics is an emerging technology that offers a simple and inexpensive alternative to traditional microfluidics. Paper is an attractive medium for microfluidic devices because of its inherent hydrophilicity and low cost. Hydrophobic materials including wax and photoresist are used to pattern the paper. The most common method for making paper microfluidic analytical devices (μPAD) is wax printing, however, this method requires an expensive and specialized printer that is limited to printing documents and channel designs. Our method uses inexpensive materials and tools accessible to most research labs in the US. We utilize 3D printers, a common tool available in many universities because of their versatility. Poly(dimethylsiloxane) (PDMS) wax stamps are used to deposit wax onto paper, forming microfluidic channels. The PDMS stamps are produced with ABS 3D printed molds designed in CAD software. A PDMS stamp is dipped into melted wax and then pressed onto paper much like the process of using a rubber stamp and ink. Once the wax is deposited, the paper is heated, letting the wax penetrate the paper and form hydrophilic channels. This rapid and simple procedure allows researchers to easily produce μPADs with the flexibility of CAD software and 3D printers.