Femtosecond laser turn droplets controllable bouncing

Droplets controllable bouncing on solid surfaces plays a vital role in microfluidic operation, liquid collection, and chemical micro reaction applications, which has attracted widespread attention. However, strategies to realize controllable bouncing of droplets on solid surface are still elusive and nanofabrication patterning methods are generally complex and time consuming. Here, we propose a simple and fast method to fabricate heterogeneously wettable surfaces on aluminum sheets by femtosecond laser processing followed by wax treatment. The surface is comprised of superhydrophobic regions with a water contact angle (WCA) of ∼ 159.5°and superhydrophilic regions with a WCA of ∼ 1.8°. The heterogeneous wettability in specific designs can control droplet bouncing motions when impacting the surface. Therefore, the liquid droplets are regulated to rotate and controllably bounce for achieving various functions, including climbing, combining, and driving small boats. This work demonstrates a facile way to fabricate patternable heterogeneous wettability surfaces for manipulating droplets and achieving multifunctional bouncing motions. Our simple, effective, and environmentally friendly method holds promise for transformative advancements in electric power generation, pharmaceutical development and manufacturing, as well as the realm of self-driving actuators.