Nanowerk

Synthetic Hydrogel Helices Amplify Movement without Muscles or Motors

The team from POSTECH and the University of Tokyo introduced a photopolymerization method that creates hydrogel helices with built‑in density gradients, enabling autonomous winding and unwinding. By using a helically wrapped UV‑blocking tape and a dissolved ruthenium absorber, they generate asymmetric swelling that transforms a straight fiber into a self‑oscillating helix. The resulting helices show amplified actuation—up to 42 % axial contraction on heating and 18 % autonomous oscillation—far exceeding comparable rod‑shaped gels. Demonstrations include soft‑robotic locomotion and chemically powered oscillations, highlighting a scalable route to muscle‑like soft actuators.