Deck the walls by tunable energy fields for colloidal particles (Data)

pThe ability to dictate colloid motion is an important challenge in fields ranging from materials science to living systems. Here, by embedding energy landscapes in conned nematic liquid crystals, we design a versatile platform to dene colloidal migration. This is achieved by placing a wavy wall with alternating hills and wells in a nematic liquid crystal to impose a smooth elastic energy field with alternating splay and bend distortions. This domain generates (meta) stable loci that act as attractors and unstable loci that repel colloids over distances large compared to the colloid radius. Energy gradients in the vicinity of these loci are exploited to dictate colloid trajectories. We demonstrate several aspects of this control, by studying transitions between defect configurations, propelling particles along well defined paths and exploiting multistable systems to send particles to particular sites within the domain. Finally, we demonstrate the ability of a colloid in motion, like \Goldilocks", to select from wells of different sizes for preferred docking. Such tailored landscapes have promise in reconfigurable systems and in microrobotics applications./p调控胶体运动的能力是材料科学乃至生命系统等诸多领域中的一项重要研究挑战。本研究通过在受限向列相液晶（nematic liquid crystals）中嵌入能量景观，构建了一种可用于定义胶体迁移行为的通用调控平台。该平台的实现方式为：在向列相液晶中引入带有交替起伏峰谷的波浪形壁面，以此构建出兼具交替展曲与弯曲形变的平滑弹性能量场。此能量场会生成兼具吸引作用的（亚）稳态位点，以及可在远大于胶体半径的距离范围内排斥胶体的非稳态位点。研究人员可利用这些位点附近的能量梯度来调控胶体的运动轨迹。本研究通过探究缺陷构型间的转变过程、引导粒子沿预设路径运动，以及利用多稳态系统将粒子输送至域内指定位置，验证了该调控平台的多项调控能力。最终，我们验证了运动中的胶体可如同“金发姑娘”一般，从不同尺寸的阱中选取适配位点以实现优先锚定。这类定制化的能量景观在可重构系统与微机器人技术领域具备广阔的应用前景。