Trimer-like microrobots with multimodal locomotion and reconfigurable capabilities

Despite the growing interest in the motion mechanisms and application potential of individual active colloids/particles in micro/nanorobotics, their aggregation for higher-ordered mesostructures remains a significant challenge due to the complexity of their motion control and dynamics. Here, a magnetic trimer-like microrobot composed of three magnetic Janus colloids with different diameters exhibited multimodal locomotion, frequency-dependent reconfigurability, and contactless manipulation in a 3D environment. Various locomotion modes excited by adjusting the magnetic field rely on different driving principles. At a low Reynolds number, trimer-like microrobots can locomote in a 3D space based on their asymmetric shape distribution and can move on a surface by breaking spatial symmetry. A strategy to reconfigure trimer-like microrobots from β-config to α-config rapidly was implemented by alternating the frequency and strength of the magnetic field. Additionally, the trimer-like microrobots follow a unique chiral rotating mode with self-adjusting capabilities under uniform rotating magnetic field propulsion in horizontal plane. Through the integration of multimodal locomotion, these trimer-like microrobots are capable of moving in complex 3D environments and manipulating passive particles without in-depth contact via fluidic mediation. These trimer-like microrobots can reconfigure their operation mode according to multitasking requirements or in response to environmental variations.