Painting Eco-friendly Microfluidic Pen-on-Paper Based Analytical Devices (μP²ADs): Economical and Facile Fabrication of μP²AD for Simultaneous Colorimetric Detection

This study introduces a cost-effective and facile methodology for the fabrication of microfluidic pen-on-paper-based analytical devices (μP<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>ADs) tailored for point-of-care diagnostics and biological assays, utilizing wax pens as a primary tool. The proposed approach employs readily accessible materials such as wax pens and filter paper, ensuring practicality and widespread applicability. The fabrication process is streamlined into three essential steps that are microfluidic channel outline drawing, wax deposition through wax pen painting, and heating to develop channels. The fabrication process is economical, facile, solvent-free, and eco-friendly as it involves direct wax deposition through painting on biodegradable paper substrate. This process eliminates the need for specialized printers with hazardous inks and advanced fabrication facilities. To evaluate the functionality and reliability of the fabricated μP<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>ADs, starch and protein identification assays were conducted. The successful performance of these assays underscores the potential of this approach to enable resource-limited settings with low-cost yet efficient analytical tools for diagnostic and biochemical applications.