Dynamically Reconfigurable-Engineered Motile Semiconductor Active Microparticles

Abstract

Locally energized particles that are powered by external fields (e.g., electrical, magnetic, optical, chemical, and thermal gradients) have formed the basis of emerging classes of reconfigurable active matter. The ability to rationally design such particles in a way to enable robust control of their assembly and reconfiguration can ultimately help this promising area to realize its full potential. Herein, we introduce a class of engineered semiconductor active microparticles that can be designed with exceptional specificity (e.g., in size, shape, electric and magnetic polarizability, and field rectification) by leveraging standard electronic fabrication tools. These particles draw energy from applied external fields and actively propel, repel, rotate, and perform on-demand sequential assembly and disassembly. We show that a number of electric field-based effects such as electrohydrodynamic (EHD) flows, induced-charge electroosmosis, induced-charge electrophoresis, and dielectrophoresis can selectively power this suite of particles. We also show that a number of magnetic field-based effects such as magnetohydrodynamic (MHD) flows and magnetophoresis can induce additional functionalities to similarly designed particles. The result is the ability to achieve customized locomotion, interactions, reversible assembly, and synchronous rotational torque on demand that could enable advanced applications such as artificial muscles, remotely powered microsensors, optical switches, and reconfigurable computational systems.