UntetheredMicro-Actuators for Autonomous Micro-robot Locomotion: Design, Fabrication, Control, and Performance

This paper presents power delivery and actuation mechanisms designed for use in autonomous mobile robots whose dimensions can be measured in tens to hundreds of micrometers. Test devices utilizing these mechanisms have been fabricated at scale using micro-electromechanical systems (MEMS) technology, and have been shown capable of untethered locomotion at speeds exceeding 1.5 mm/sec (scale-comparable to the speed of an automobile). The power delivery mechanism operates through a capacitive coupling with a silicon substrate that underlies the mobile device. This allows the device actuation mechanism to use electrostatic forces (which scale favorably to magnetic forces as device size is decreased to the hundred micrometer range) without requiring any physical connection or wire that would restrain the motion of the device. Through appropriate design of the substrate wiring and actuator geometries, the power delivered to the device can be shown to be independent of the device’s position and orientation. For this reason, this power delivery mechanism is appropriate for fully two-dimensional (x, y) and (x, y, θ) mobile microrobots. The actuation mechanism consists of a scratch drive actuator [1,2], which has for the first time been shown to be operable without physically-restraining electrical tethers such as rails, stators, or springs. Because scratch drive actuators are capable of fast speeds and also nanometer-scale precision, they are a promising choice for the actuators of mobile microrobots.