Developed at UC San Diego, the researchers placed a thin layer of liquid crystal elastomer actuators in critical areas across soft skin. The robot was directed by adjusting the pressure within its body and the temperature of its actuators.
The researchers demonstrated that a robot outfitted with this skin could effectively navigate a replica of the arteries in the human body and a model of the inside of a jet engine.
Our work represents a step toward small, steerable, soft vine robots for applications in delicate and constrained environments.
Tania K. Morimoto, Study Corresponding Author and Associate Professor, Department of Mechanical and Aerospace Engineering, University of California San Diego
Researchers overcome size constraints by placing a series of actuators made of liquid crystal elastomer at strategic points in a soft, robotic skin. These actuators are exceedingly small yet extremely robust, making them ideal for steering robots on a small scale.
The robot may be controlled via temperature, pressure, or both. The study team found that controlling the robots by both temperature and pressure is the best option.
Morimoto added, “[The team] embedded small, flexible heaters under the actuators to control the actuator's temperature and built a system to precisely adjust the pressure inside the robot for steering.”
Researchers tested the skin on a flexible vine robot three to seven mm (approximately 0.2 inches) in diameter and 25 cm (roughly 10 inches) long. These robots expand from the tip by flipping their skin inside out. When the actuators were turned on, the robot could make several turns of more than 100 degrees throughout its body length.
The robot could also fit through tight gaps, including some that were half its diameter. For example, researchers were able to thread a soft vine robot through a model of a human aorta and a connecting artery. They also connected the robot to a camera to check several targets within a complex jet engine model.
The soft skin developed in this work could further be adapted for other various soft robotic systems, such as wearable haptic devices, soft grippers, and locomotive soft robots.
Sukjun Kim, Postdoctoral Researcher, University of California San Diego
The next steps involve allowing the robot to be commanded remotely or autonomously, as well as making it smaller.
The National Institutes of Health (R01 EB032417) and the Arnold and Mabel Beckman Foundation funded this study. The results were reported in the journal Science Advances.
This Robotic Skin Allows Tiny Robots to Navigate Complex, Fragile Environments
A vine robot equipped with the active skin navigates a model of a jet engine and a model of human arteries. Video Credit: University of California San Diego
Journal Reference:
Kim, S. et.al. (2025) LCE-integrated soft skin for millimeter-scale steerable soft everting robots. Science Advances. doi.org/10.1126/sciadv.adw8636.