Unidirectional movement behavior of underwater bubbles on the wettability gradient mesh via asymmetrical bounce

The impact of underwater bubbles on solid surfaces with a gradient wettability is important for fundamental science and technological applications. Despite progress in the translational motion of underwater bubbles on asymmetric surface, a fundamental dynamic understanding of asymmetrical bounce behavior of the underwater bubble needs to be further improved. Herein, we investigate asymmetrical bounce of underwater bubbles after impacting the wettability gradient copper mesh surface. Asymmetrical bounce of the underwater bubble on the wettability gradient mesh (WGM) surface is composed by asymmetrical spread in the spread process and asymmetrical recoil in the recoil process, which induce the unidirectional movement behavior. Additionally, effective bubble-size manipulation can be easily implemented due to different volumes of bubbles remaining at different locations of WGM surface. We envision that this work will provide a new understanding of asymmetrical bounce behavior of the underwater bubble on the wettability gradient surface, and propose a novel and feasible strategy for constructing the underwater bubble manipulation system.