School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China.
Soft Matter. 2018 Sep 19;14(36):7462-7468. doi: 10.1039/c8sm01056k.
Manipulation of underwater bubbles is of great importance in both scientific research and industrial applications. In this work, the motion of underwater bubbles on a microholed polydimethylsiloxane (PDMS) surface with gradient wettability is studied using a high-speed camera. It was found that underwater bubbles self-transported directionally from the smaller area fraction (SAF) to the larger area fraction (LAF) of the surface. Besides, the bubble motion was triggered by an effective depth range from hcr,min to hcr,max. Only the depth of the bubble was within the range when the self-transport motion occurred. Otherwise the bubble would adhere onto the surface eventually. The main cause for the motion is the trapped air inside the microholes, which generates the torque Tb and the retention force Fr driving the bubble directionally. The mathematical model is established to reveal the motion mechanism, which is verified by the experimental results. The outcomes of our work shed new light on the target transportation fields such as drug delivery and submarine gas collection.
水下气泡的操控在科学研究和工业应用中都具有重要意义。在这项工作中，使用高速摄像机研究了具有梯度润湿性的微孔聚二甲基硅氧烷（PDMS）表面上水下气泡的运动。结果发现，水下气泡会从较小的面积分数（SAF）自传输到较大的面积分数（LAF）的表面。此外，气泡的运动是由有效深度范围 hcr,min 到 hcr,max 触发的。只有当气泡的深度在自传输运动发生的范围内时，气泡才会发生运动。否则，气泡最终会附着在表面上。运动的主要原因是微孔内的被困空气，它会产生扭矩 Tb 和保留力 Fr，从而使气泡定向运动。建立了数学模型以揭示运动机制，并通过实验结果进行了验证。我们工作的结果为药物输送和潜艇气体收集等目标输送领域提供了新的思路。
