Soft everting robots grow from the tip through eversion, allowing them to move with minimal interaction with their surroundings. To navigate complex environments and perform tasks such as manipulation, they require actuators and mechanisms for steering, stiffening, and retraction. Miniaturizing these components is a significant challenge, which led us to develop methods for embedding them directly into the robot’s skin. We created a variety of functionalized skins for millimeter-scale soft everting robots by incorporating liquid crystal elastomers, magnetic elastomers, and pneumatic pouches.

The frictionless locomotion of soft everting robots makes them well-suited for safely navigating the human body. We developed a hybrid architecture that combines a hydraulically actuated soft growing robot with a tendon-driven notched continuum robot. This system successfully steers around the most difficult aortic arch (Type III), and deploys a 2.67 mm-diameter growing robot from its tip, which pulls an aspiration catheter through highly tortuous vessels. This approach enables active steering in proximal anatomy and navigation in complex distal vessels, with potential to reduce procedure times and expand access to care.

In another design, we integrated magnetic elastomeric skin into an 8 mm-diameter robot, allowing it to steer under external magnetic fields. This fully soft robot could squeeze through gaps smaller than the robot diameter and successfully navigate to various peripheral locations in a bronchial tree phantom.