Boymelgreen Alicia, Yossifon Gilad, Park Sinwook, Miloh Touvia
Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion, Israel Institute of Technology, Haifa 32000, Israel.
School of Mechanical Engineering, University of Tel-Aviv, Tel-Aviv 69978, Israel.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jan;89(1):011003. doi: 10.1103/PhysRevE.89.011003. Epub 2014 Jan 16.
We provide an experimental proof of concept for a robust, continuously rotating microstructure-consisting of two metallodielectric (gold-polystyrene) Janus particles rigidly attached to each other-which is driven in uniform ac fields by asymmetric induced-charge electro-osmosis. The pairs (doublets) are stabilized on the substrate surface which is parallel to the plane of view and normal to the direction of the applied electric field. We find that the radius of orbit and angular velocity of the pair are predominantly dependent on the relative orientations of the interfaces between the metallic and dielectric hemispheres and that the electrohydrodynamic particle-particle interactions are small. Additionally, we verify that both the angular and linear velocities of the pair are proportional to the square of the applied field which is consistent with the theory for nonlinear electrokinetics. A simple kinematic rigid body model is used to predict the paths and doublet velocities (angular and linear) based on their relative orientations with good agreement.
我们提供了一个概念验证实验，该实验针对一种坚固的、持续旋转的微观结构——由两个刚性连接在一起的金属电介质（金-聚苯乙烯）双面粒子组成——其在均匀交流电场中由不对称感应电荷电渗驱动。这些粒子对（双联体）稳定在与观察平面平行且与外加电场方向垂直的基底表面上。我们发现，粒子对的轨道半径和角速度主要取决于金属半球和电介质半球之间界面的相对取向，并且电流体动力学粒子间相互作用较小。此外，我们验证了粒子对的角速度和线速度都与外加电场的平方成正比，这与非线性电动学理论一致。基于它们的相对取向，使用一个简单的运动刚体模型来预测路径和双联体速度（角速度和线速度），结果吻合良好。
