Creating a Softer RoboSquid: Liquid‐Metal‐Based Compliant Pumps for Pulsed Jet Propulsion

Abstract

Abstract Soft pumps are a crucial element in biology, from our own hearts to actuators driving the motion of many creatures in nature. For example, the squid is one of the fastest and most powerful animals in the ocean despite being almost entirely soft, using controlled jets by compressing an internal chamber to propel itself rapidly through the water. Duplicating this performance in an artificial system has, however, remained challenging. Here, a novel soft electromagnetic pump based on using coils of room temperature LM (liquid metal) to drive a permanent magnet piston is demonstrated and used to propel a squid‐inspired vehicle. Liquid gallium alloys in silicone tubing are used to manufacture a stretchable electromagnet which is then integrated into a silicone bubble and used to actuate an attached permanent magnet. The robosquid here was able to achieve as high as 4.53 cm s −1 (0.65 body lengths/s) and 9.52 cm s −1 (1.38 body lengths/s) average and peak speed respectively, competitive with current squid inspired vehicles integrating rigid motors and actuators. This result is a major milestone in creating high performance pumps for soft robotics, and will enable superior performance of future soft underwater vehicles leveraging biological principles.