Comparison of microPADs pre- and post-miniaturization. (A) Photograph of a wax-printed microPAD displaying high fidelity of the miniaturization process. (B) Scanning electron microscope (SEM) surface images of Whatman No. 1 chromatography (CHR) paper (400X magnification). Fibers appear to be more compact following miniaturization. (C) SEM cross-sectional images of Whatman No. 1 CHR paper (200X magnification). Miniaturized microPADs displayed a 166% increase in cross-sectional height (thickness). Part C reprinted by permission from Springer Nature, Cellulose22, 2018.