Fast-moving piezoelectric micro-robotic fish with double caudal fins

Abstract Micro-robotic fish (length ≤ 10 cm) driven by smart materials have remarkable advantages over conventional motors and piston-based robotic fish. In particular, they are highly efficient and compact. One of the key challenges is attaining high mobility with high energy density, low driving voltage and power loss. In this work, a double caudal fin micro-robotic fish actuated by two piezoelectric bimorph cantilevers is proposed and fabricated from rigid carbon fiber/resin composites and flexible polyimide hinges. Its weight is about 1.93 g and the maximum uniform swimming velocity is as high as about 0.75 BL/s (4.5 cm/s), which is much faster than previously reported micro-robotic fish actuated by ionic polymer-metal composites, shape memory alloys and dielectric elastomers. A theoretical model is validated by the experimental results and can be used to design and analyze a variety of piezoelectric robotic fish propelled by caudal fins.