2026 ASEE Annual Conference & Exposition

Paper microfluidics is a field of interest for applications such as DNA detection, diagnostic tools, and environmental pollution tracking. Previously, in the junior Bioengineering laboratory class at the University of Pennsylvania, the paper microfluidics lab module was conducted by printing and then baking a wax layer onto Whatman filter paper. Taking inspiration from an experiment testing Washburn flow in a paper channel shaped with a CO2 laser to cut and seal edges, backed nitrocellulose paper and a VLS 3.60DT laser cutter were used to develop a new version of the lab module. The goal of this paper is to create a procedure for the paper microfluidics module with a laser cutter that could be scaled to function in Bioengineering classes of various sizes and skill levels. Incorporating updated technology, such as the laser cutter, allows students to use equipment available to them in makerspaces. It was found that the procedure not only maintained the integrity of Washburn assumptions but also was better received by students.

We developed a procedure using cameras, rulers, and video analysis software to track the path of the fluid front to determine its adherence to the Washburn equation. To demonstrate functionality, 31 paper channels were tested and analyzed for a power relationship with a 95% CI of [0.465, 0.481] (μ = 0.47, σ = 0.02). This average power relationship closely follows the 0.5 expected from the Washburn relationship. A survey was used to make a comparison between classes of subsequent years, with one class (n=47) using a laser, while the other (n=12) used a wax printer for fabrication. All but two questions from the survey showed statistically significant differences in responses from the two groups. The most notable differences in survey responses for laser cutter usage were in the consistency of paper microfluidic fabrication (average 49.3% increase in strong agreement), understanding of practical application (average 43.7% increase in strong agreement), and overall frustration with the module (47.8% decrease in strong agreement). There were a few limitations encountered with our current experimental setup that could be addressed in future iterations of this lab module. Namely, the minimum feature size was not limited by the width of the laser beam, but rather by charring from the cutting process and the inherent transient period needed for Washburn-like flow. Some future directions for this lab entail the application of Darcy flow, characterization of flow from channels that intersect, as well as three-dimensional channels.