to yield an SU-8 layer with a thickness of 100 µm. We used a photomask (12700 dpi, Unno Giken, Tokyo, Japan) designed using Adobe Illustrator CC 2017 (Adobe, San Jose, CA, USA) and a mask aligner (M-1S, Mikasa Shoji) to introduce ultraviolet (UV) light. The SU-8 mold was treated with trichloro(1H,1H,2H,2H-perfluorooctyl)silane vapor and PDMS was poured onto the molds to yield the microfluidic device.