Modular reconfiguration and actuation of microrobotic assemblies

Transport in microfluidic systems occurs under low-Reynolds-number conditions, where localized particle manipulation requires controlled fluid-structure interaction. Here, a modular magnetic microfluidic robotic assembly was developed using soft-bodied, hard-magnetic, and arc-shaped modules that self-assembled under external magnetic fields, underwent oscillatory actuation, and reversibly disassembled within the same platform. Field modulation enabled transitions between force- and torque-dominated regimes, allowing periodic deformation to be transmitted from the actuated legs to the functional head region. During oscillatory actuation, particles were redistributed via contact-assisted sweeping, accompanied by localized fluid disturbance. Forward and backward transport efficiencies of 91.1% ± 3.6% and 92.1% ± 2.6% were achieved, with a round-trip retention efficiency of 83.8% ± 4.8%. Frequency-dependent analysis identified an actuation condition that balanced deformation transmission and actuation rate. This work provides a basis for programmable microrobotic transport and localized manipulation in confined microfluidic environments.