Phase‐Change Alloys Enable Localized Reversible Stiffening and Actuation in Steerable Eversion Tip‐Growing Robots

Tip‐growing eversion robots navigate complex, constrained environments through pressure‐driven shear‐free material unfolding at the tip—a locomotion strategy ideal for intraluminal interventions. However, their flexibility limits their force exertion and payload delivery, makes them prone to buckling under compressive loads, and causes reliance on environmental support in tortuous pathways. To address this, phase‐changing low‐melting point alloy media are introduced to simultaneously achieve localized reversible stiffening and fluidic actuation. By modulating the alloy's thermal state, the robot switches between compliant and rigid states, achieving a stiffness ratio of 43‐ and a 15‐fold force increase. A bespoke steerable catheter within the robot's lumen locally modulates heating and steering, enabling for the first time segmental control and hybrid soft‐rigid eversion robot morphologies. To unlock robust, selective actuation and prevent thermal damage, the system's thermal response is optimized through spatial profiling and timing control of heating cycles. This ensures rapid, localized phase transitions without thermal spillover. The robot demonstrates physically intelligent stiffening and navigation, selectively isolating mechanical forces and adapting its morphology to fit the task at hand. Its capabilities are validated in constrained pathway navigation, force delivery, and steerability, highlighting its potential for next‐generation intraluminal interventions and soft robotic platforms.