(398e) Field-Driven Dynamics of Metallo-Dielectric Particles and Particle Ensembles: From Programmed Assembly to Directed Motility and Actuation

Metallo-dielectric particles, such as Janus and patchy spheres, and selectively coated microcubes, acquire complex polarization pattern in electrical fields, which can lead to multidirectional dielectrophoretic interactions. In addition, such particles exhibit a variety of AC electrokinetic motility effects (also known as induced charge electrophoresis). The combination of dielectrophoresis and AC electrokinetic motility, controlled through the field frequency, strength and direction, opens a rich field of possibilities for engineered assembly and manipulation on the microscale. We will discuss the origins of the polarization and electrokinetic effects in systems of Janus and patchy particles and how they can be controlled and directed. One of the specific topics that has emerged from these studies is how complex directional polarization interactions (quadrupolar, hexapolar and multipolar) can be induced by external electric and magnetic fields and can be used to assemble new types of staggered chains, networks and crystals of unusual symmetry. We will examine how the particle assembly motifs and the structure of the small clusters formed can be analyzed via numerical calculations of the field intensity and energy in particle-medium polarization models. The assembly of permanent, yet reconfigurable, structures can be achieved with the additional use of magnetic fields and metal coatings with residual polarization. Overall, the field-driven assembly and dynamics of metallo-dielectric particles offers facile tools for making and actuation of numerous types of dynamic microscale structures, which may find applications in emerging fields such as soft robotics, microrobotics, and active and reconfigurable microfluidic devices. This potential will be illustrated in a preliminary way by a few examples of motile and self-folding particle assemblies.