Voß Johannes, Wittkowski Raphael
Institut für Theoretische Physik, Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany.
ACS Nano. 2022 Mar 22;16(3):3604-3612. doi: 10.1021/acsnano.1c02302. Epub 2022 Mar 9.
Previous studies on ultrasound-propelled nano- and microparticles have considered only systems in which the particle orientation is perpendicular to the direction of propagation of the ultrasound. However, in future applications of these particles, they will typically be able to attain other orientations. Therefore, using direct acoustofluidic simulations, here we study how the propulsion of triangular nano- and microparticles, which are known to have a particularly efficient acoustic propulsion and are therefore promising candidates for future applications, depends on their orientation relative to the propagation direction of a traveling ultrasound wave. Our results reveal that the propulsion of the particles depends strongly on their orientation relative to the direction of wave propagation and that the particles tend to orient perpendicularly to the wave direction. We also address the orientation-averaged translational and angular velocities of the particles, which correspond to the particles' effective propulsion for an isotropic exposure to ultrasound. Our results allow assessment of how free ultrasound-propelled colloidal particles move in three spatial dimensions and thus constitute an important step toward the realization of envisaged future applications of such particles.
先前关于超声驱动的纳米粒子和微米粒子的研究仅考虑了粒子取向垂直于超声传播方向的系统。然而，在这些粒子的未来应用中，它们通常能够获得其他取向。因此，我们在此使用直接声流体模拟来研究三角形纳米粒子和微米粒子的推进如何取决于它们相对于行波超声传播方向的取向，已知这些粒子具有特别高效的声推进，因此是未来应用的有前途的候选者。我们的结果表明，粒子的推进强烈取决于它们相对于波传播方向的取向，并且粒子倾向于垂直于波方向取向。我们还研究了粒子的取向平均平动速度和角速度，它们对应于粒子在各向同性超声照射下的有效推进。我们的结果有助于评估自由的超声驱动胶体粒子在三个空间维度中的运动方式，从而朝着实现此类粒子设想的未来应用迈出重要一步。
