Walid Rezanoor Md, Dutta Prashanta
School of Mechanical and Materials Engineering, Washington State University , Pullman, Washington 99164-2920, USA.
Biomicrofluidics. 2016 Mar 2;10(2):024101. doi: 10.1063/1.4943032. eCollection 2016 Mar.
Electrorotation is widely used for characterization of biological cells and materials using a rotating electric field. Generally, multiphase AC electric fields and quadrupolar electrode configuration are needed to create a rotating electric field for electrorotation. In this study, we demonstrate a simple method to rotate dielectrophoretically trapped microparticles using a stationary AC electric field. Coplanar interdigitated electrodes are used to create a linearly polarized nonuniform AC electric field. This nonuniform electric field is employed for dielectrophoretic trapping of microparticles as well as for generating electroosmotic flow in the vicinity of the electrodes resulting in rotation of microparticles in a microfluidic device. The rotation of barium titanate microparticles is observed in 2-propanol and methanol solvent at a frequency below 1 kHz. A particle rotation rate as high as 240 revolutions per minute is observed. It is demonstrated that precise manipulation (both rotation rate and equilibrium position) of the particles is possible by controlling the frequency of the applied electric field. At low frequency range, the equilibrium positions of the microparticles are observed between the electrode edge and electrode center. This method of particle manipulation is different from electrorotation as it uses induced AC electroosmosis instead of electric torque as in the case of electrorotation. Moreover, it has been shown that a microparticle can be rotated along its own axis without any translational motion.
旋转电场广泛用于使用旋转电场对生物细胞和材料进行表征。通常，需要多相交流电场和四极电极配置来创建用于旋转电场的旋转电场。在本研究中，我们展示了一种使用静态交流电场旋转介电泳捕获的微粒的简单方法。共面叉指电极用于创建线性极化的非均匀交流电场。这种非均匀电场用于微粒的介电泳捕获以及在电极附近产生电渗流，从而导致微流体装置中的微粒旋转。在频率低于1kHz的2-丙醇和甲醇溶剂中观察到钛酸钡微粒的旋转。观察到高达每分钟240转的粒子旋转速率。结果表明，通过控制施加电场的频率，可以对粒子进行精确操纵（包括旋转速率和平衡位置）。在低频范围内，观察到微粒的平衡位置在电极边缘和电极中心之间。这种粒子操纵方法与旋转电场不同，因为它使用感应交流电渗而不是旋转电场情况下的电转矩。此外，已经表明微粒可以沿其自身轴旋转而没有任何平移运动。
