Fabrication of paper-based microfluidic devices using a 3D printer and a commercially-available wax filament

In this work, we developed an alternative manufacturing paper-based microfluidics method through 3D printing and wax filament. Microfluidic paper-based analytical devices (µPADs) are low-cost and easy-to-manufacture tools used for various chemical and biological analyses and studies. Paper-based microfluidics with wax has been limited as the manufacturers have discontinued most wax printing equipment. We aim to develop a low-cost and accessible manufacturing method that can replace conventional wax-on paper-based microfluidic manufacturing methods. Using highly available commercial 3D printing technology and wax filament, we could create hydrophobic wax barriers on the surface of different paper types. The properties and limits of this manufacturing method were characterized. Moreover, using this paper-based microfluidic manufacturing method, we were able to measure dopamine electrochemically using µPAD as a passive flow-based method in concentrations as low as 1 nM using injections as small as 15 µL.