• • Electrically actuated microrobots are defined by a strict physical envelope of <5 cm in length and <5 g in mass, a scale at which external field-generation equipment for magnetic or optical actuation becomes cost-prohibitive and hardware-redundant; this establishes electrical actuation as the only viable pathway for centimeter-scale autonomous systems requiring untethered operation.
• • The review identifies power supply and control strategy as the two dominant bottlenecks limiting autonomous operation and long-duration mission execution, with both factors being determined by the employed actuation mechanism; this directly implies that material-level energy density and drive voltage thresholds dictate the operational endurance and mission profile of any microrobot platform.
• • Material electromechanical performance parameters—specifically actuation strain, blocking force, and energy efficiency—are shown to directly govern obstacle-crossing ability and energy utilization efficiency, creating a quantifiable trade-off space where material selection for a given locomotion mode is constrained by the specific strain-force-energy triad of the functional material.
• • The distinct electromechanical properties of different material types determine their applicability to specific locomotion modes, meaning that no single material system satisfies all locomotion requirements; this necessitates a mission-specific material selection framework rather than a universal actuator solution, with direct implications for design cycle time and system integration complexity.