Individual closed-loop control of micromotors by selective light actuation†

Abstract

Control of individual micromotors within a group would allow for improved efficiency, greater ability to accomplish complex tasks, higher throughput, and increased adaptability. However, independent control of micromotors remains a significant challenge. Typical actuation techniques, such as chemical and magnetic, are uniform over the workspace and therefore cannot control one micromotor independently of the others. To address this challenge, we demonstrate a novel control method of applying a localized region of UV light that activates a single light-responsive TiO₂ micromotor at a time. To achieve this, a digital micromirror device (DMD) was employed which is capable of highly precise localized illumination. To demonstrate this precise user-defined control, patterns of micromotors were created via selective actuation and magnetic steering. In addition, a closed-loop system was also developed which automates the guidance of individual micromotors to specified locations, illustrating the potential for more efficient and precise control of the micromotors.