Propulsion Method for Swimming Microrobots

This paper presents a novel swimming method mediated by traveling waves in elastic tails. The propulsion method is potentially appropriate for maneuvering microrobots inside the human body. The swimming action relies on the creation of a traveling wave along a piezoelectric layered beam divided into several segments. This requires that a voltage with the same frequency, but different phases and amplitudes, be applied to each segment. The swimming pattern was analyzed theoretically by solving the coupled electric-elastic-fluidic problem, and was optimized to attain reasonable thrust. It was found that despite extreme size limitations, a tail manufactured by current microelectromechanical-devices technology, using piezoelectric material, is able to swim in water at a speed of several centimeters per second. The swimming theory was verified experimentally using an upscaled model that produced propulsion of 0.04 mN, which matches closely the theoretically predicted propulsion.