Optoelectrowettability conversion on superhydrophobic CdS QDs sensitized TiO ₂ nanotubes

This work demonstrates the process of building optoelectrically cooperative surface wetting in smart and precise way. The superhydrophobic photosensitive film is constructed with TiO ₂ nanotube arrays. Compared with conventional organic dyes, CdS quantum dots (QDs) as sensitizer layer are modified on TiO ₂ nanotubes surface to improve photosensitivity of the composited surface in visible light region, which offer the benefit for designing and fabricating solid state hetero-junction devices. ITO glass is introduced as top electrode to apply electrical and optical stimuli and the patterned wetting is instantly obtained with masking light through ITO. The optoelectrically cooperative wettability conversion occurred on superhydrophobic TiO ₂ nanotube surface at critical voltage of 12V, which was decreased by 18V comparing with only using electric stimulus. This study provides potential applications for TiO ₂ nanotube arrays to the associated research of liquid reprography, location-controlled microfluidic device and lab-on-chip.