Dr. Tania K. Morimoto, Associate Professor of Mechanical and Aerospace Engineering at UC San Diego, leads a team that has developed a novel soft robotic skin enabling vine robots just a few millimeters wide to steer through complex, delicate spaces. Their results, point toward new possibilities for inspection, medical intervention, and structural surveying in confined or fragile settings.
Kim, S., Dong, G., Mangan, A., Agrawal, D., Cai, S., & Morimoto, T. K. (2025). LCE-integrated soft skin for millimeter-scale steerable soft everting robots. Science Advances, 11(42). https://doi.org/10.1126/sciadv.adw8636
In the lab, the team constructed a “skin” layer embedded with actuators made of liquid crystal elastomer (LCE). These actuators are placed at strategic locations around the body of a soft vine robot. By controlling internal pressure and the temperature of the actuators, the robot can bend, turn, and squeeze through narrow passages. The researchers demonstrated the technology by navigating the robot through models of human arteries and the interior of a jet engine.
Soft vine robots are not new; they grow from their tip by everting their outer skin inward, allowing extension without external pulling. However, steering methods at very small scales (millimeter range) remain challenging. Traditional steering mechanisms—pneumatics, tendons, motors—are difficult to scale down, suffer in miniaturized form, or add bulk that limits maneuverability.
Dr. Tania K. Morimoto, Associate Professor of Mechanical and Aerospace Engineering at UC San Diego stated,
“They 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.”
Morimoto’s group addressed this by integrating thin strips of LCE material directly into the skin. When heated (via flexible microheaters) these strips contract or deform, creating a local curvature. Combined with adjustments in pressure inside the robot’s body, the system allows fine steering control. The dual-mode control (temperature + pressure) proved more effective than either mode alone.
In experiments, the team used vine robots of diameters between 3 and 7 mm (roughly 0.12–0.28 inches) and lengths of about 25 cm. They showed the robot could produce bends exceeding 100° along its body length. The robot also compressed through gaps as narrow as half its diameter. In one trial, it successfully threaded through a model of the human aorta and connecting vessel. In another, it traversed a mock-up jet engine internal space. The tip of the robot carried a small camera to inspect features inside the engine model.
At the heart of the innovation is the use of LCE as a soft actuator material. Liquid crystal elastomers combine elasticity with ordered molecular structure: when heated, they change shape in a controlled way. (LCEs are a known class of materials used in actuators and soft robotics.) Because the strips are thin and embedded, they minimally increase bulk but still generate sufficient bending moment.
One engineering challenge is balancing the heating and response of actuators with pressure control. Heat must be localized and responsive, yet not damage or over-stress the soft body. The thermal control system includes flexible heaters beneath the LCE strips. Pressure control regulates stiffness and extension. The coordination of these two controls is key to achieving smooth and precise steering.
Material durability under repeated actuation, heat cycling, and friction against confining walls are additional concerns. Over time, fatigue or micro-tears in the soft skin or actuators may degrade performance. The team acknowledges the need for future work on reliability, lifespan, and scaling down further.
This soft skin design for millimeter-scale vine robots opens doors to applications in areas where rigid robots cannot venture. In medical contexts, such robots could inspect blood vessels, deliver therapy, or assist in minimally invasive interventions without damaging tissues. In industrial settings, they might access tight structural cavities—such as inside turbines, engines, or complex piping; for inspection, maintenance, or repair.
The researchers suggest that the skin concept might also be adapted for other soft robotics: wearable haptics, soft grippers, or locomotion devices. The modular nature of embedding actuators into soft surfaces means similar strategies could scale or vary across form factors.
Looking ahead, the team plans to develop remote-controlled or autonomous versions of the robot. They also aim to reduce its footprint further—making it smaller in diameter or length, while maintaining steering capability and robustness. Improving control algorithms, sensor integration, and system autonomy are next steps.
Recent news summaries and press releases highlight this development as a notable advance in soft robotics. For example, the UC San Diego press office underscores that the system allows vine robots to traverse models of arteries and jet engines. Media outlets such as EurekAlert! and Interesting Engineering emphasize the thin LCE actuator strips and their combination with pressure control to steer robots in constrained spaces.
Interest in LCE‐based actuation is growing in soft robotics. Because LCEs can respond to stimuli like temperature or light, they offer compact and tunable actuation without large mechanical linkages. In parallel, other research projects are exploring how to embed sensors, energy sources, or intelligence within soft robots to increase autonomy.
Of course, broader challenges remain before such robots become practical in real-world tasks. Reliability over repeated cycles, maintaining performance in fluid or variable environments, integration with wireless control, and ensuring safety in biological settings all require further study.
Under Dr. Morimoto’s leadership, the integration of soft LCE actuators into the skin of millimeter-scale vine robots represents a meaningful step toward steerable soft machines for delicate environments. The work shows that actuation and control at very small scales can be achieved through clever materials engineering rather than brute mechanical subsystems.
As research continues, such robots may one day navigate inside living tissues, examine inaccessible industrial machinery, or perform inspections in confined, sensitive areas. The advance underscores a broader trend in robotics: moving from rigid machines to soft, adaptive systems that can operate in places once thought unreachable.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
