Printing Motion Directly Into Soft Machines
Researchers at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new 3D printing method that allows soft robots to move straight out of the printer. Instead of adding motors, hinges, or complex assemblies, the team programs motion directly into the robot’s structure. As a result, the printed machines bend, twist, and grasp objects as soon as engineers activate them.
A Single-Step Alternative to Molding
Conventional soft robots rely on molds and multiple fabrication stages to create internal channels that drive movement. The Harvard team replaces this slow process with rotational multimaterial 3D printing. Using a specially designed nozzle, the printer deposits a flexible outer polymer alongside a removable inner ink. By rotating the nozzle during printing, the researchers precisely control the orientation and geometry of internal channels.
After printing, the team washes away the temporary inner material, leaving behind hollow channels inside the soft structure. When air flows through these channels, the robot deforms exactly as designed. This approach enables engineers to fabricate complex soft actuators in a single step, eliminating the need for molds, assembly, or manual intervention.
Demonstrating Complex Movements
To demonstrate the technique’s capabilities, the researchers printed spiral structures that unfurl like blooming flowers when inflated. They also created a soft robotic hand with finger-like segments that bend at knuckle-style joints. These demonstrations show how carefully designed channel patterns can produce coordinated, lifelike motion.
Expanding Possibilities for Soft Robotics
This fast and programmable printing method could significantly accelerate the development of soft robots for medical tools, wearable devices, and applications that require gentle manipulation. By embedding movement directly into printed materials, the research moves soft robotics closer to practical, scalable real-world use.
