Planar fluidic channels on TiO2 nanoparticle coated paperboard

A new design for permanent, low-cost, and planar fluidic channels on TiO₂ nanoparticle coated paperboard is demonstrated. Initially superhydrophobic TiO₂ nanoparticle coatings can be converted to hydrophilic by ultraviolet (UVA) light, and fluidic channels can be generated. A simple water treatment after the UVA illumination converts the channels permanent when nanoparticles are removed from the illuminated and wetted areas as shown by water contact angle, FE-SEM, XPS, and ToF-SIMS analysis. This suggests new routes for inexpensive, easy to use point-of-care diagnostics based on planar fluidic channels.