Titanium Oxide Nanoparticle Coating of PMMA Open Flow Channels for Spontaneous Water Transport

Nanoparticle coating is a potential technique for conferring functional properties to solid surfaces. The appli-cation of a titanium oxide (TiO2) nanoparticle coating to polymethyl methacrylate (PMMA) open flow channels was investigated herein. Open flow channels with the widths of 0.5-1 mm were fabricated by milling. The effect of TiO2 coating on the wettability of PMMA surface was examined by water contact angle measurements. The data show that nanoparticle coating was applicable to both square and round flow channels. The particle con-centration of TiO2 affected the evenness of the coating layer. Using TiO2-coated channels, spontaneous water flow was demonstrated, whereas the bare PMMA channel did not allow water flow. The spontaneous flow conditions observed here were summarized using the generalized Cassie angle. Finally, the possibility of selective liquid transport was demonstrated using parallel TiO2-coated and uncoated flow channels stemming from a single fluid inlet. This work offers a potential technique of nanoparticle coating for extending the applications of open flow channels.