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.

水下气泡对具有梯度润湿性的固体表面的影响对于基础科学和技术应用非常重要。尽管水下气泡在不对称表面上的平移运动取得了进展，但对水下气泡不对称弹跳行为的基本动态理解还需要进一步改进。在这里，我们研究了水下气泡在撞击润湿性梯度铜网表面后的不对称弹跳。水下气泡在润湿梯度网格(WGM)表面上的不对称弹跳是由扩散过程中的不对称扩散和反冲过程中的不对称反冲组成的，从而诱发单向运动行为。此外，由于 WGM 表面不同位置保留的气泡体积不同，因此可以轻松实现有效的气泡尺寸控制。我们预计这项工作将为水下气泡在润湿性梯度表面上的不对称弹跳行为提供新的理解，并为构建水下气泡操纵系统提出一种新颖且可行的策略。