Patterned liquid permeation through the TiO₂ nanotube array coated Ti mesh by photoelectric cooperation for liquid printing

The surface wettability response has been intensively studied under external stimulus, and the cooperation of different stimuli seems a trend for more effective surface wetting. Despite much progress in this field, the patterning of controllable surface wettability is still a challenge, which is a very important issue for printing techniques. Here, we have developed an approach for the photoelectric cooperative wetting induced liquid permeation through a TiO2 nanotube array coated Ti mesh. The patterned liquid permeation can be realized by patterned light illumination under a voltage which is lower than the electrowetting induced permeation threshold voltage. The permeation process and mechanism are discussed in detail. The results indicate that the microscale movement of a liquid can be controlled precisely by the surface micro/nano hierarchical structure of the device, with a low adhesion and responsive voltage. Therefore, this work is important in the research and application of liquid printing, moreover, it provides a new approach to develop and apply novel devices such as micro/nanofluidic systems, microreactors and micro-nanoelectronic technologies.