Fabrication of Bio-inspired Superamphiphobic Aluminum Alloy Surface with Oil-triggered Wenzel-Slippery Transition via Femtosecond Laser

Surface-tension-confined microfluidic devices are platforms for manipulating 2D droplets based on patterned surfaces with special wettability. They have great potential for various applications, but are still in the early stages of development and face some challenges that need to be addressed. This study, inspired by the Wenzel and slippery transition of rose petal, develops a Patterned Oil-triggered Wenzel-slippery Surface (POWS) to examine the microfluidic devices. A laser-chemical composite method is established to fabricate POWSs, which take rose-petal-like microstructures as wettability pattern and a superamphiphobic surface as the background. The prepared POWSs switched between high adhesion superhydrophobic state and the slippery liquid-infused surface state through adding or removing the lubricant oil. In the high adhesion superhydrophobic state, the droplets can be sticked on the surface. In the slippery liquid-infused state, the droplet can slide along the wettability pattern as the designed route. A POWS-based droplet reactor is further constructed, on which, the droplets can be remotely controlled to move, mix and react, as required. Such a POWS, which manipulates droplets with surface tension controlled by the switchable wettability patterns, would be a promising candidate to construct multiple surface-tension-confined microfluidic devices. In addition, the fabrication technique and design principle proposed here may aid the development of various field related to the bio-inspired surfaces, such as water collection, desalination and high throughput analysis, etc.