Novel, simple and low-cost alternative method for fabrication of paper-based microfluidics by wax dipping

Paper-based microfluidic devices are an alternative technology for fabricating simple, low-cost, portable and disposable platforms for clinical diagnosis. Hereby, a novel wax dipping method for fabricating paper-based microfluidic devices (μPADs) is reported. The iron mould for wax dipping was created by a laser cutting technique. The designed pattern was transferred onto paper by dipping an assembly mould into melted wax. The optimal melting temperature and dipping time were investigated. The optimal melting temperature was in the range of 120-130 °C, and the optimal dipping time was 1 s. The whole fabrication process could be finished within 1 min without the use of complicated instruments or organic solvents. The smallest hydrophilic channel that could be created by the wax dipping method was 639 ± 7 μm in size. The reproducibility of the μPAD fabrication for hydrophilic channel width of the test zone and sample zone was 1.48% and 6.30%, respectively. To verify the performance of the μPAD, multiple colorimetric assays for simultaneous detection of glucose and protein in real samples were performed. An enzymatic assay and the bromocresol green (BCG) method were conducted on the paper device to determine the presence of glucose and protein in a test solution. The results of the assays were not significantly different from those of the conventional methods (p > 0.05, pair t-test and one-way ANOVA method). The wax dipping provides a new alternative method for fabricating lab-on-paper devices for multiple clinical diagnostics and will be very beneficial for developing countries.