SPatterned papers were fabricated using previously described methods [42,47]. Briefly, the transparency film photomask was designed with Adobe Illustrator CS5 software (Adobe Systems, Inc.) and printed by Chaiyaboon Co. (Bangkok, Thailand). The filter paper was coated with 4 g of SU-8 negative photoresist using a spin coater (G3P-8). After baking at 95 ◦C for 10 min, the photomask was placed above the coated paper and exposed to ultraviolet (UV) light with 100% intensity for 10 s (Intelli-ray 400). Areas exposed with UV light remained hydrophobic whilst unexposed areas were hydrophilic. The exposed paper was baked at 95 ◦C for 10 min followed by soaking in the SU-8 developer and then isopropanol for 3 min each, respectively. Finally, the patterned paper was dried in a hood at room temperature (22±2 ◦C). Prior to use, paper microfluidic devices were exposed to air plasma (Harrick PDC-32G) for 2 min.