Princeton 3D prints soft robot that moves with electric current

Princeton engineers just printed a soft robot that moves with electric current and never needed a conventional motor to do it. The crane-shaped demo flaps its wings when powered, then returns to its original form again and again without noticeable degradation, which is the kind of repeatable motion that makes soft robotics feel a lot less like a lab stunt and a lot more like a future printable mechanism.

The work appeared online March 21 in Advanced Functional Materials in a paper titled Digital Actuation Control of Soft Robotic Origami With Self-Folding Liquid Crystal Elastomer Hinges. David Bershadsky, Tuo Zhao, Glaucio Paulino and Emily Davidson used a 3D printer to pattern a printable polymer called liquid crystal elastomer, then paired it with flexible electronics and origami-inspired folding to build a soft-rigid hybrid robot. Instead of a motor or external pneumatic control, the motion came from targeted heating inside the polymer.

That detail is the one worth keeping in mind if you print, tune, or hack on mechanisms for fun: the action was built into the material stack, not bolted on afterward. Princeton says the robot could repeatedly move without noticeable degradation and could return to its original shape without wear or distortion through real-time programmable sequences. In plain maker terms, that is the difference between a one-off demo and a part that might survive a long test cycle without turning into a warped, tired mess.

Getting anything like this into a home shop would take a lot more than a standard spool swap. You would need printable liquid crystal elastomer formulations that behave predictably, a way to integrate flexible conductors or electronics cleanly, and process control tight enough to place soft and rigid regions exactly where they belong. You would also need dependable, localized electrical heating that stays consistent enough to drive motion without cooking the part or throwing off the fold geometry. Right now, that is far beyond the usual desktop workflow.

Princeton’s own robotics trail helps explain why this result matters. The university pointed to earlier soft-robot work in 2024 on modular multi-degree-of-freedom soft origami robots with reprogrammable electrothermal actuation, then to a 2025 metamaterial called a metabot that responded to magnetic fields. This latest crane pushes the same idea further, with a printed structure that can be reconfigured, actuated and reset with precision. Supported in part by Princeton’s Kamran Rafieyan ’89 Fund for Undergraduate Research and Princeton University Project support, it is a sharp reminder that the next useful robot parts may not be assembled so much as printed into existence.