From lab to rubble: can this lightning-fast origami robot be the future of search and rescue?

Imagine soft robots scurrying through rubble with the agility of geckos or leaping over obstacles with the dynamism of frogs—capabilities that would prove invaluable in post-disaster rescue and exploration missions. In recent years, soft robotics has emerged as a prominent focal point of academic research, owing to its intrinsic compliance, inherent operational safety, and superior environmental adaptability. Yet, endowing soft robots with biological-grade agility and speed has long remained a pivotal challenge that researchers strive to address.

Currently, most soft robots face a "performance shackle" in practical applications: they are often slow and weak in mobility. This limitation stems from a trade-off in soft actuators, where it is difficult to achieve high-speed response, large strain and force output simultaneously. Consequently, soft robots have long been stuck in a "slow-motion" phase, unable to perform high-mobility tasks in the real word.

To overcome the inherent "sluggishness" of traditional soft robots and enable high-speed, agile movements on par with their natural counterparts, a research team from Tongji University has carried out in-depth research—findings recently published in the journal SmartBot. Inspired by the synergistic "skeletal-muscle" mechanism of vertebrates, the team proposed a "rigid-flexible" solution: merging the geometric topology of origami with high-performance electrohydraulic actuators. This novel Electrohydraulic Origami (EHO) actuator uses a hexagonal rigid frame to act as a "skeleton" and electrohydraulic units to serve as "muscles". By applying high voltage to the flexible electrodes, the resulting electrostatic force squeezes the liquid dielectric, thereby driving the rotation of the origami joints. This design cleverly leverages the amplification and transmission principles of both structure and mechanics, transforming minute electrohydraulic zipping motions into massive, high-speed and multimodal structural deformations of the origami framework. 

By integrating soft electrohydraulic actuation with origami structures, the EHO actuators unlock entirely new actuation modes while delivering remarkable dynamic performance. Experimental results indicate that an EHO actuator with a 10-cm arm length can achieve a staggering axial strain of up to 3300% and a peak strain rate exceeding 23500 %/s—outperforming most existing soft actuators. Meanwhile, a smaller 2.5-cm-arm version can perform vertical jumps 8.5 times its own height without any external energy storage components. Furthermore, even under a 100 g load—equivalent to 12.5 times its own weight—the actuator maintained an impressive 483.3% actuation strain, demonstrating exceptional load-bearing capacity. Various robotic prototypes powered by EHO actuators demonstrate exceptional locomotion capabilities. Notably, the tethered crawling soft robot can achieve an average linear speed of 37.55 cm/s (approximately 9.39 body lengths per second) and a rapid turning velocity of 211.5°/s. Furthermore, the wireless version, equipped with a miniature high-voltage control system, delivers average speeds that outpace most previously reported untethered crawling soft robots driven by electroactive soft actuators. Moreover, the robot can crawl steadily on a 15.6° incline and perform agile maneuvers along S-shaped paths. These capabilities mark a significant milestone in transitioning electrohydraulic robots from laboratory prototypes toward untethered, practical applications like field exploration, search-and-rescue, and human-machine interactions, etc.

About Tongji University

Tongji University is a prestigious comprehensive research university located in Shanghai, China. As a member of the "Double First-Class" initiative, it excels in engineering, architecture, urban planning, and environmental science, with several disciplines ranked among the world’s top. Boasting world-class faculty, cutting-edge laboratories, and extensive global collaborations with leading institutions, Tongji prioritizes innovative research and interdisciplinary education. It nurtures talented professionals dedicated to addressing national and global challenges, making remarkable contributions to urban development, sustainable technology, and social progress.

Website: https://www.tongji.edu.cn/

About Dr. Wenbo Li from Tongji University, China

Dr. Li graduated from Shanghai Jiao Tong University, China in 2019 with a Doctor of Philosophy (PhD) degree in Mechanical Engineering. After completing a two-and-a-half-year postdoctoral research fellowship at the State Key Laboratory of Mechanical System and Vibration, he joined Tongji University as a research professor of the School of Aerospace Engineering and Applied Mechanics in 2022. His research interests include soft robots, smart materials and structures. He has published about 40 peer-reviewed papers in journals including Nature Communications, Science Advances, SmartBot, Advanced Functional Materials, etc. He also holds approximately 20 authorized Chinese patents.

Funding information

This work was supported by National Natural Science Foundation of China (Grants 12472057, 12532002, and 12102398), General Project of the Shanghai Natural Science Foundation (Grant 24ZR1468800), Research Project of State Key Laboratory of Mechanical System and Vibration (Grant MSV202407), Fundamental Research Funds for the Central Universities, and Shanghai Gaofeng Project for University Academic Program Development.