School of Engineering, University of Edinburgh, Edinburgh EH9 3FB, United Kingdom.
Nano Lett. 2021 Feb 10;21(3):1267-1273. doi: 10.1021/acs.nanolett.0c03895. Epub 2021 Jan 25.
Ultrasonic surface vibration at high frequencies ((100 GHz)) can nucleate bubbles in a liquid within a few nanometres from a surface, but the underlying mechanism and the role of surface wettability remain poorly understood. Here, we employ molecular simulations to study and characterize this phenomenon, which we call acoustothermal nucleation. We observe that nanobubbles can nucleate on both hydrophilic and hydrophobic surfaces, and molecular energy balances are used to identify whether these are boiling or cavitation events. We rationalize the nucleation events by defining a physics-based energy balance, which matches our simulation results. To characterize the interplay between the acoustic parameters, surface wettability, and nucleation mechanism, we produce a regime map of nanoscopic nucleation events that connects observed nanoscale results to macroscopic experiments. This work provides insights to better design a range of industrial processes and clinical procedures such as surface treatments, mass spectroscopy, and selective cell destruction.
高频（100GHz）超声表面振动可以在距表面几纳米的范围内使液体中的气泡成核，但其中的潜在机制和表面润湿性的作用仍知之甚少。在这里，我们采用分子模拟来研究和描述这一现象，我们称之为声致热核化。我们观察到纳米气泡可以在亲水和疏水表面上成核，并使用分子能量平衡来确定这些是沸腾还是空化事件。我们通过定义基于物理的能量平衡来合理化成核事件，该平衡与我们的模拟结果相匹配。为了描述声参数、表面润湿性和成核机制之间的相互作用，我们制作了一个纳米级成核事件的区域图，将观察到的纳米级结果与宏观实验联系起来。这项工作为更好地设计一系列工业过程和临床程序提供了思路，例如表面处理、质谱和选择性细胞破坏。
