Directional Motion and Adhesion of Tiny Droplets on Bioinspired Spindle-Knotted TiO2 Fibers

Bioinspired TiO2 fibers with periodic spindle knots were prepared, whose surface showed responsive wettability and adhesion. The responsive wettability of these fibers was intellectually controlled by micro/nano structures of fibers and environmental stimulation such as ultraviolet and ultrasonic. Based on controlled wettability of bioinspired TiO2 fibers, tiny water droplets could not only move directionally from joint to spindle knot but also be captured by fiber spindle knots. When the fibers are hydrophilic, tiny water droplets always move directionally whatever the surface of fibers is smooth or rough. When the fibers become hydrophobic, tiny water droplets on the fibers firstly move from both ends to center of spindle knots, and then are adhered by spindle knots with rough surface.