title: Patterning of wettability for controlling capillary-driven flow in closed channels.
abstract: Glass capillaries are prepared with well-defined regions of tuneable wettability on the interior walls using an inexpensive and simple approach. A homogeneous layer of hydrophilic TiO2 nanoparticles is adsorbed on the capillary wall and chemically hydrophobized using octadecyltrihydrosilane (OTHS). The hydrophobic OTHS monolayer is then patterned by spatially-selective removal of the OTHS via TiO2-catalysed decomposition by ultraviolet irradiation. By patterning the capillaries with hydrophilic-hydrophobic rings, modulated penetration of a liquid (glycerol, in this study) can be achieved. For given wettability contrast, the penetration dynamics and equilibrium rise heights are very sensitive to the characteristic length-scale of the pattern, and may offer greater, time-dependent sampling control in fluidic devices.
authors: Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors: Muireann
authors: M
authors: O'Loughlin
authors: Craig
authors: C
authors: Priest
authors: Mihail N
authors: MN
authors: Popescu
authors: John
authors: J
authors: Ralston