Simple biodegradable plastic screen-printing for microfluidic paper-based analytical devices

Abstract

The goal of using microfluidic paper-based analytical devices (μPADs) in remote areas has prompted the development of uncomplicated, affordable, and environmentally-friendly fabrication methods. Here, screen-printed biodegradable polycaprolactone (PCL) as a simple, low-cost, and non-toxic alternative approach to create μPADs was introduced. No need for a heating step contributed to low PCL dispersion resulting in high resolution hydrophobic barriers. The proposed method achieved a narrowest hydrophilic channel and hydrophobic edge of 510 ± 40 μm and 490 ± 30 μm, respectively. The method was used to generate several designs for Cr3+ and Cl− detections. For Cr3+ analysis, silver nanoparticles were used as the colorimetric probe to selectively measure Cr3+ using a spot format that achieved a limit of detection (LOD) of 15.0 μg L-1 and a linear working range of 50.0–1000.0 μg L-1. For Cl- determination, the distance-based pattern using traditional precipitation titration was utilized to resolve the coffee ring effect from colorimetric detection. The method gave an LOD and a linear range for Cl- detection of 10.0 mg L-1 and 10.0–500.0 mg L-1, respectively. Finally, the μPADs were applied for Cl- analysis in instant noodle seasonings and the results significantly agreed with those using the traditional titration at 95 % confidence.