On‐Board Mechanical Control Systems for Untethered Microrobots

An autonomous robot perceives its environment, makes decisions based on acquired information and programmed routines, and then actuates a movement or performs a manipulation task within that environment. The idea of microrobotics is primarily based on teleoperated mobile micromachines equipped with manipulation capabilities such as actuated grippers and drug‐loaded reservoirs. Due to miniaturization challenges, the majority of these micromachines are wirelessly actuated using magnetic fields or acoustic waves. A step toward complete autonomy is the development of on‐board control systems that directly transduce environmental stimuli such as heat and pressure into actuation, without going through the perception and computation cycles. Following the analogy of the central nervous system for the architecture of conventional autonomous robots, the next‐generation microrobots are expected to possess reflexes that would allow them to autonomously navigate inside structured microenvironments and perform targeted and triggered operations. Herein, the construction of on‐board control systems using stimuli–responsive materials, nonlinear mechanical mechanisms, and fluid–structure interactions is described. Recent advances in macroscale soft robotics and mechanical metamaterials are highlighted with the hope that they inspire solutions for microrobotics.