The device was fitted with a twisted and coiled polymer (TCP) to drive it forward, a light-weight low-cost device that relies on temperature change to generate movement.
The mechanism works by contracting like muscles when heated, with the energy being converted into mechanical motion.
The robot fish uses a TCP which is warmed by Joule heating – the passage of current through an electrical conductor produces thermal energy and heats up the conductor. By minimising the distance between the TCP on one side of the robot fish and the spring on the other, this activates the fin at the rear, enabling the robot fish to reach high speeds.
The undulating flapping of its rear fin was measured at a frequency of 2Hz, two waves per second. The frequency of the electric current is the same as the frequency of tail flap.
Lead author Tsam Lung You from Bristol’s Department of Engineering Mathematics said: “Twisted and coiled polymer actuator is a promising novel actuator...