Depto. Electrónica y Electromagnetismo, Universidad de Sevilla, Sevilla, Spain.
Electrophoresis. 2013 Apr;34(7):979-86. doi: 10.1002/elps.201200403. Epub 2013 Mar 11.
Electrorotation (ROT) data for solid titanium micrometer-sized spheres in an electrolyte are presented for three different ionic conductivities, over the frequency range of 10 Hz to 100 kHz. The direction of rotation was found to be opposite to the direction of rotation of the electric field vector (counterfield electrorotation), with a single rotation peak. The maximum rotation rate occurs at a frequency of the order of the reciprocal RC time constant for charging the particle double layer capacitance through the resistor of the electrolyte bulk. A model for the electrical torque acting on a metallic sphere is presented, using a constant phase element impedance to describe the metal/electrolyte interface. The titanium spheres are much denser than the electrolyte and rest on the bottom substrate. Therefore, the electrical and viscous torques near a wall are considered in the analysis. Good agreement is found between the predicted and measured rotational speed as a function of frequency. Theory shows that there is no effect of induced charge electroosmotic flow on the ROT, as observed experimentally.
本文提供了在三种不同离子电导率下，固态钛微球体在电解质中的旋电（ROT）数据，频率范围为 10 Hz 至 100 kHz。发现旋转方向与电场矢量的旋转方向相反（反电场旋电），出现单个旋转峰值。最大旋转速率出现在通过电解质本体电阻对颗粒双电层电容进行充电的 RC 时间常数倒数量级的频率。提出了一种作用在金属球上的电扭矩模型，使用恒相元件阻抗来描述金属/电解质界面。钛球体比电解质密度大，且位于底部基底上。因此，在分析中考虑了壁附近的电和粘性扭矩。预测的旋转速度与实验观察到的旋转速度与频率的关系非常吻合。理论表明，如实验所观察到的，感应电荷电渗流对 ROT 没有影响。
