Racing-car-inspired electrical/chemical dual-driven actuators for swimming Marangoni robots based on carbon nanotube composites

Swimming robots driven by the Marangoni effect have attracted considerable research interest recently. Current Marangoni actuators are mostly chemical-driven or light-driven. However, simultaneously achieving high actuation speed and programmable motions remains a persistent challenge. Herein, inspired by multi-mode propulsion strategies employed in high-performance racing cars, we propose electrical/chemical dual-driven Marangoni actuators fabricated from carbon nanotube-cellulose fiber (CNT-CF) and polyethylene (PE) composites. Firstly, under electrical stimulation, the actuator exhibits programmable self-propelled swimming locomotion (linear and turning motions) on water surfaces. The actuation mechanism is due to the temperature gradient generated by Joule-heating. Secondly, upon dissolution of an embedded bone glue film, the actuator operates in a purely chemical-driven Marangoni mode, generating rapid autonomous swimming locomotion. Critically, when both electrical and chemical stimuli are applied, the actuator enters a dual-driven mode through a synergistic effect, attaining a velocity of 32.2 mm s^-1, exceeding the arithmetic sum of individual electrical-driven (5.4 mm s^-1) and chemical-driven (11.3 mm s^-1) velocities by over 93%. Furthermore, the same CNT-CF/PE material system can fabricate actuators showcasing on-land crawling motions. Finally, two actuators are assembled to a functional robotic gripper, demonstrating the versatility of platform. This work establishes a unified design paradigm for state-of-the-art actuators and multifunctional amphibious devices.