Supercolloidal Spinners: Complex Active Particles for Electrically Powered and Switchable Rotation
Supercolloidal Spinners: Complex Active Particles for Electrically Powered and Switchable Rotation
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DOI：
10.1002/adfm.201803465
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发表时间：
2018-08-29
影响因子：
19
通讯作者：
Velev, Orlin D.
中科院分区：
文献类型：
--
作者：
Shields, Charles Wyatt;Han, Koohee;Velev, Orlin D.
报道了一类在交流电场中可控地绕中心轴旋转的超胶体粒子。这些“微调器”的合理设计使它们能够以可切换的方式旋转，这产生了几个有趣的和可编程的行为。结果表明，由于其复杂的形状和离散的金属补丁在其表面上，这些微自旋器转换成积极的运动通过四个机制在不同的电场频率范围内的相互作用的电能。这些旋转机制包括（按频率增加的顺序）：电流体动力学流动，反向电流体动力学流动，诱导电荷电泳和自介电电泳。当为它们的运动提供动力的主要机制从一种现象过渡到下一种现象时，这些微旋转器显示出三个方向的旋转反转（即，从顺时针到逆时针，或反之亦然）。为了了解所涉及的机制，这项实验研究与缩放分析相结合。由于其频率可切换的旋转，这些微旋转器具有潜在的应用，如在胶体微机械联锁齿轮。此外，用于为其可切换运动提供动力的原理可以扩展到设计其他类型的超胶体粒子，这些粒子通过多种电动机制为运动收集电能。
A class of supercolloidal particles that controllably spin about their central axis in AC electric fields is reported. The rational design of these "microspinners" enables their rotation in a switchable manner, which gives rise to several interesting and programmable behaviors. It is shown that due to their complex shape and discrete metallic patches on their surfaces, these microspinners convert electrical energy into active motion via the interplay of four mechanisms at different electric field frequency ranges. These mechanisms of rotation include (in order of increasing frequency): electrohydrodynamic flows, reversed electrohydrodynamic flows, induced charge electrophoresis, and self-dielectrophoresis. As the primary mechanism powering their motion transitions from one phenomenon to the next, these microspinners display three directional spin inversions (i.e., from clockwise to anticlockwise, or vice versa). To understand the mechanisms involved, this experimental study is coupled with scaling analyses. Due to their frequency-switchable rotation, these microspinners have potential for applications such as interlocking gears in colloidal micromachines. Moreover, the principles used to power their switchable motion can be extended to design other types of supercolloidal particles that harvest electrical energy for motion via multiple electrokinetic mechanisms.