Beyond Wax Printing: Fabrication of Paper-Based Microfluidic Devices Using a Thermal Transfer Printer.

Paper-based microfluidic devices, also known as microPADs, are an emerging analytical platform with the potential to improve point-of-care diagnostics. MicroPADs are fabricated by patterning hydrophobic inks onto sheets of paper to create hydrophilic channels and test zones. One of the main advantages of microPADs is that they are inexpensive and simple to fabricate, making them accessible even to researchers with limited budgets or no prior fabrication expertise. Wax printing, where a solid ink printer is used to pattern wax on paper, has been the most convenient and popular method for fabricating paper-based microfluidic devices. Unfortunately, solid ink printers were discontinued in 2016 and are no longer available commercially. Here we introduce a method for fabricating microPADs using a portable thermal transfer printer that retains the convenience of wax printing. Devices fabricated by thermal transfer printing were comparable to devices fabricated via wax printing and laser printing. The low cost, convenience, and portability of the thermal transfer printer make this approach an exciting prospect for replacing wax printing and facilitating the continued development of paper-based microfluidics.