Advancing paper microfluidics: A strategic approach for rapid fabrication of microfluidic paper-based analytical devices (µPADs) enabling in-vitro sensing of creatinine

•This Research advances paper-based sensors, optimizing hydrophobic microchannel (µPAD) fabrication.•The approach employs a modified DIY RepRap 3D printer combined with a technical drawing pen loaded with PDMS-hexane mixture.•The colorimetric detection of creatinine concentrations in artificial urine spans from 5 mg/dL to 450 mg/dL, with naked eye.•The limiting concentration of 500 mg/dL and an estimated Limit of Detection (LOD) of 61.4 mg/dL.•Nylon 6,6 membrane microfluidic domains display concentration-dependent Janovsky complexes, demonstrating high selectivity. Paper-based microfluidic sensors for point-of-care applications represent an exceptional strategy for facilitating rapid sensing within clinical settings. Despite their considerable promise, the ongoing research objective lies in efficiently printing hydrophobic microfluidic channels (µPADs) onto hydrophilic paper while minimizing expenditure. This research paper introduces an advanced, economic, and efficient method for the rapid fabrication of µPADs on paper substrates, enabling immediate colorimetric detection of creatinine in artificial urine using Jaffe’s reagent. The process involves a modified DIY RepRap 3D printer with an integrated technical drawing pen filled with the solution of Polydimethylsiloxane (PDMS) and hexane. This solution creates hydrophobic domain barriers on a flexible nylon-based paper substrate, effectively confining the aqueous medium within the microfluidic channels. We report visual detection of a broad spectrum of creatinine concentrations ranging from 5 mg/dL to 450 mg/dL through the vibrant Janovsky complex appearance on the microfluidic domains. The study identifies the limiting concentration on µPADs as 500 mg/dL. The innovative procedure demonstrates exceptional selectivity, exhibiting a maximum interference of only 0.97 % from potentially interfering substances. This rapid, naked-eye detection of creatinine on nylon 6,6 membranes offers a user-friendly and economical approach, enhancing the capabilities of colorimetric visualization in point-of-care applications.