Rapid fabrication of paper-based microfluidic analytical devices with desktop stereolithography 3D printer

In this study, we developed a novel and facile method for fabricating paper-based microfluidic analytical devices (mu PADs) with dynamic mask photo curing (DMPC), generated by a desktop stereolithography (SL) three-dimensional printer (3DP). First, we immersed the filter paper in ultraviolet (UV) resin to cover it evenly. Next, we exposed it to UV-light through a dynamic mask of the negative channel pattern. After curing, the UV-exposed regions become highly hydrophobic, creating hydrophobic barriers. Finally, we washed the uncured resin with anhydrous alcohol and fine mPADs were obtained. The resolution of the fabricated hydrophilic channels was 367 +/- 20 mu m, with a between-channel hydrophobic barrier of 400 +/- 21 mu m. To verify this method's performance, we fabricated mu PADs with DMPC for quantitative analysis of nitrite ion. This new method represents a leap forward in terms of time saved. Since all hydrophobic barriers are cured at a time, the fabrication process can be completed in only two minutes, no matter how complex the patterns are. Compared to the widely used fabrication method of mu PADs, wax printing, DMPC provides an alternative way to fabricate mu PAD with different hydrophobic barriers materials, which provides the possibility of designing different mPADs according to the application environments.