Figure 1.

High-resolution fabrication of multiplex paper-based microfluidic devices using a pen plotter machine and high-resolution technical pens. (a) Desktop pen plotter with a high-resolution technical pen. (b) High-resolution technical pen with 0.1 mm plastic tip used for patterning hydrophobic solution to create detection zones. (c) Technical pen nib with 0.1 mm plastic tip used for patterning hydrophobic solution on paper substrate. (d,e) Cross-section of chromatography paper (d), chromatography paper after being coated with hydrophobic solution using the wide marker (e), regenerated paper (f), and corresponding circular pattern (2 mm diameter) on those paper substrates. The yellow food dye is applied to the hydrophilic side of paper to distinguish it from hydrophobic side.