Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India.
Soft Matter. 2018 Feb 28;14(9):1719-1736. doi: 10.1039/c7sm02297b.
The axisymmetric electrohydrodynamic deformation of an elastic capsule with a capacitive membrane obeying the Skalak law under a uniform AC electric field is investigated using analytical and boundary integral theory. The low capillary number (the ratio of destabilizing shear or electric force to the stabilizing elastic force) regime shows that time-averaged prolate and oblate spheroid deformations, and the time-periodic prolate-sphere, oblate-sphere breathing modes are commensurate with the time averaged-deformation. A novel prolate-oblate breathing mode is observed due to an interplay of finite membrane charging time and the field reversal of the AC field. The study, when extended to high capillary numbers, shows new breathing modes of cylinder-prolate, cylinder-oblate, and biconcave-prolate deformation. These are the results of highly compressive normal Maxwell stress at the poles and are aided by a weak compressive equatorial stress, characteristic of a capacitive membrane. The findings of this work should form the basis for the understanding of more complex biological cells and synthetic capsules for industrial applications.
采用解析和边界积分理论研究了在均匀交流电场作用下服从 Skalak 定律的电容膜弹性胶囊的轴对称电动力学变形。在低毛细数（失稳剪切或电力与稳定弹性力的比值）条件下，时间平均的长椭球和扁椭球变形以及周期性的长球-扁球呼吸模式与时间平均变形一致。由于有限的膜充电时间和交流场的反转的相互作用，观察到一种新颖的长椭球-扁球呼吸模式。当扩展到高毛细数时，研究显示出圆柱-长椭球、圆柱-扁球和双凹-长椭球变形的新呼吸模式。这些是在极处的高度压缩的法向 Maxwell 应力的结果，并由一个较弱的压缩赤道应力辅助，这是电容膜的特征。这项工作的结果应该为理解更复杂的生物细胞和用于工业应用的合成胶囊奠定基础。
