Microbubbles generated by the photothermal conversion using a laser beam induce strong convective flow and can accumulate nanoparticles over a long distance. This study investigates the accumulation process of nanoparticles with a diameter of 100 and 300 nm using two experimental setups that enable bottom- and lateral-view observations. The bottom-view and SEM observations reveal that the particles are accumulated at and near the three-phase contact line. The bottom-view observation also shows that the particle deposition at an early stage is not axisymmetric, which contradicts a model proposed earlier. The asymmetric accumulation is also observed by the lateral view. The lateral view further reveals that the particles in bulk first adhered to the bubble surface and moved to the three-phase contact line by interfacial flow. It is also suggested that the amount of the particles accumulated on the surface is not proportional to the bubble volume (bubble radius to the third power) but proportional to the bubble radius to the fourth power. This is explained by a difference in temperature distribution on the bubble surfaces.

使用激光束光热转换产生的微气泡会引起强烈的对流，并可以长距离积累纳米粒子。本研究使用两种能够进行仰视和侧视观察的实验装置来研究直径为 100 和 300 nm 的纳米粒子的积累过程。底视图和 SEM 观察表明颗粒在三相接触线处和附近积累。仰视观察还表明，早期的颗粒沉积不是轴对称的，这与之前提出的模型相矛盾。侧视图也观察到不对称积累。侧视图进一步表明，散装颗粒首先附着在气泡表面，并通过界面流移动到三相接触线。还建议表面上积累的颗粒量与气泡体积（气泡半径的三次方）不成正比，而是与气泡半径的四次方成正比。这是由气泡表面温度分布的差异来解释的。