Masukawa Marcos K, Hayakawa Masayuki, Takinoue Masahiro
Department of Computer Science, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8502 Japan.
Department of Computational Intelligence and Systems Science, School of Computing, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8502 Japan
RSC Adv. 2020 Mar 2;10(15):8895-8904. doi: 10.1039/d0ra00703j. eCollection 2020 Feb 27.
This study examined the effects of surfactants on the motion and positioning of microparticles in an inhomogeneous electric field. The microparticles were suspended in oil with a surfactant and the electric field was generated using sawtooth-patterned electrodes. The microparticles were trapped, oscillating, or attached to the electrodes. The proportion of microparticles in each state was defined by the concentration of surfactant and the voltage applied to the electrodes. Based on the trajectory of the microparticles in the electric field, we developed a new physical model in which the surfactant adsorbed on the microparticles allowed the microparticles to be charged by contact with the electrodes, with either positive or negative charges, while the non-adsorbed surfactant micellizing in the oil contributed to charge relaxation. A simulation based on this model showed that the charging and charge relaxation, as modulated by the surfactant concentration, can explain the trajectories and proportion of the trapped, oscillating, and attached microparticles. These results will be useful for the development of novel self-assembly and transport technologies and colloids sensitive to electricity.
本研究考察了表面活性剂对非均匀电场中微粒运动和定位的影响。微粒悬浮于含有表面活性剂的油中，电场由锯齿形电极产生。微粒被捕获、振荡或附着于电极上。每种状态下微粒的比例由表面活性剂浓度和施加于电极的电压决定。基于微粒在电场中的轨迹，我们建立了一个新的物理模型，其中吸附在微粒上的表面活性剂使微粒通过与电极接触而带电，电荷可为正或负，而在油中形成胶束的未吸附表面活性剂则有助于电荷弛豫。基于该模型的模拟表明，由表面活性剂浓度调制的充电和电荷弛豫能够解释被捕获、振荡和附着微粒的轨迹及比例。这些结果将有助于新型自组装和传输技术以及对电敏感的胶体的开发。
