Distinctive Prototyping of Paper-Based Microfluidic Devices via Capillary-Driven Wax Patterning.

In this study, we introduce a novel hybrid technique for fabricating two-dimensional paper-based microfluidic analytical devices (μPADs) that combines capillary-driven wax patterning with embossing. The method utilizes capillary action to guide molten wax through a sealed polydimethylsiloxane microfluidic chip onto a glass substrate, where it forms high-resolution wax stamps upon demolding. The wax-glass assembly is then heated to facilitate wax penetration through the paper matrix, creating well-defined hydrophobic-hydrophilic barriers. This process allows precise control over stamp dimensions, offering considerable design flexibility. We systematically examined the relationship between flow time and channel length, with experimental results showing strong consistency with a modified Lucas-Washburn model developed in this study. Furthermore, the technique supports seamless integration of biological and chemical sensors into patterned μPADs, enabling the fabrication of fully functional devices. Our results highlight the robustness and scalability of this combined approach, achieving a remarkably reduction of cost. Combined with its operational simplicity, this method is particularly suitable for large-scale applications in resource-limited environments.