Soft robots can now be 3D printed to move exactly as designed

Harvard engineers have developed an innovative 3D printing technique that enables soft robots to bend, twist, and change shape in precisely programmed ways when inflated. This method integrates shape-morphing behavior directly into the printed structure by creating flexible filaments with embedded hollow channels that act as pneumatic pathways. Unlike traditional soft robotics fabrication—which relies on molds, layered casting, and complex assembly—this approach uses rotational multimaterial 3D printing with a single nozzle that deposits multiple materials simultaneously. By controlling nozzle rotation, flow rate, and geometry, the researchers can precisely position and shape internal channels, which, when pressurized, cause predictable motion such as bending or twisting. The team demonstrated the technique by printing a flower-like actuator that opens and curls and a hand-shaped gripper with articulated joints, all in a single continuous print. The printed structures use a tough polyurethane outer shell and a removable gel-like inner core, which is washed away to form hollow channels. This process eliminates the need for molds and multi-step