Fig. 5. The paper-based device fabricated by the gloss lacquer spraying method, showing: (a) the hydrophobic (left side) and hydrophilic (right side) areas captured under an
optical microscope at 4 Â magnification, (b) the hydrophilic zone soaked with food dye color and (c) a comparison of the hydrophilic and hydrophobic areas of the paper
after applying a drop of colored food dye.