Researchers from Guangdong University of Technology and Guangdong Polytechnic Normal University have developed a lightweight amphibious soft robot capable of responding to three environmental stimuli—temperature, humidity, and magnetic fields. The research, published in the Journal Center of Harbin Institute of Technology, introduces a multi-layered soft actuator designed to perform coordinated operations across land and water.
The soft robot draws its design inspiration from the locomotion and behavior of ants and whirligig beetles, which exhibit rapid, adaptive responses to environmental changes. Conventional soft robots typically rely on a single external stimulus and are limited to specific environments. Efforts to integrate multiple stimuli have faced technical challenges, particularly interference among response mechanisms that undermine operational reliability.
To address these limitations, the research team developed a composite material composed of three distinct functional layers. The base layer, made from polyimide (PI), undergoes chemical modification to form a polyamic acid (PAA) layer that is responsive to temperature and humidity. A separate silicone rubber layer embedded with neodymium iron boron (NdFeB) magnetic particles is bonded to this structure, adding magnetic responsiveness. The separation of functional layers allows the robot to maintain stable actuation under varied and overlapping environmental conditions.
The resulting device weighs 8 milligrams and is capable of reaching surface speeds of 9.6 centimeters per second—equivalent to about 32 body lengths per second—on water. It operates using a rolling motion powered by a rotating magnetic field, allowing it to cross between aquatic and terrestrial environments, navigate inclines, and maneuver around obstacles.
In demonstration experiments, the robot successfully transported an object weighing 2.5 times its own mass over a segmented terrain path. Upon reaching its target location, localized heating from near-infrared light triggered a shape change in the actuator, prompting the robot to release the cargo. Once the stimulus was removed, the robot returned to its original form and completed its retreat under magnetic control.
According to the authors, this triple-responsive design offers a functional platform for soft robots operating in environments that are currently inaccessible to conventional robotic systems. Possible applications include infrastructure inspection in submerged or hazardous locations, environmental monitoring, and payload delivery in disaster-response scenarios.
