论文标题
孤子引起的液晶启用电泳
Soliton-induced liquid crystal enabled electrophoresis
论文作者
论文摘要
通过均匀的电场(称为电泳)对颗粒进行操纵,用于广泛的应用中。特别是由交流电流(AC)驱动的电泳,因为它消除了电极阻塞并产生稳定的运动。 AC电泳的已知机制要求粒子或周围培养基是不对称的。这种不对称通常在应用磁场之前得到保证,例如Janus Spheres。我们报告了一种新的AC电泳机制,其中仅当磁场超过一定的阈值时,对称性才会损坏。新机制植根于电泳培养基的性质,这是一种定向有序的列液晶。在阈值以下,围绕球形粒子的分子方向的导演场是四极对称性的。在阈值之上,导演围绕包含在包含的范围内形成了极地自限制的扰动,该扰动随施加场的频率振荡并推动球体。导演的扰动在拓扑上是微不足道的,代表了诸如孤立波,称为“导演子弹”或“ Directrons”之类的粒子。电泳传输的方向可以由场的频率控制。当禁止其他电泳模式(如诱导的电荷电泳)时,AC导诱导的液晶启用电泳可用于运输微观货物。
Manipulation of particles by a uniform electric field, known as electrophoresis, is used in a wide array of applications. Of especial interest is electrophoresis driven by an alternating current (AC) as it eliminates electrode blocking and produces a steady motion. The known mechanisms of AC electrophoresis require that either the particle or the surrounding medium are asymmetric. This asymmetry is usually assured before the field is applied, as in the case of Janus spheres. We report on a new mechanism of AC electrophoresis, in which the symmetry is broken only when the field exceeds some threshold. The new mechanism is rooted in the nature of electrophoretic medium, which is an orientationally ordered nematic liquid crystal. Below the threshold, the director field of molecular orientation around a spherical particle is of a quadrupolar symmetry. Above the threshold, the director forms a polar self confined perturbation around the inclusion that oscillates with the frequency of the applied field and propels the sphere. The director perturbations are topologically trivial and represent particle like solitary waves, called "director bullets" or "directrons". The direction of electrophoretic transport can be controlled by the frequency of the field. The AC directron induced liquid crystal enabled electrophoresis can be used to transport microscopic cargo when other modes of electrophoresis such as induced charge electrophoresis are forbidden.