Harvard University researchers have developed a new 3D printing method that allows for the creation of soft robots with complex, pre-programmed movements without the need for laborious assembly. The technique, detailed in the journal Advanced Materials, promises to significantly accelerate the development of adaptable machines for applications in medicine and industry.
The innovation centers around a process called Rotational Multimaterial 3D Printing (RM-3DP). This method utilizes a rotating nozzle to simultaneously deposit two materials: a durable polyurethane forming the flexible body of the robot, and a gel-like polymer that serves as a temporary material for creating internal channels.
By precisely controlling the rotation and material flow, the researchers create a filament with a programmed internal structure. After the gel is washed away, precisely positioned hollow channels remain. Applying air pressure to these channels causes the material to predictably deform, functioning as a programmable artificial muscle, according to the Harvard team. “The desired motion is embedded directly into the structure during printing,” the team explained.
Traditional methods for fabricating soft robots have been time-consuming and inflexible, often involving multi-step casting, layering, and the painstaking placement and sealing of pneumatic lines. Each design iteration required a complete restart of the manufacturing process. RM-3DP bypasses these obstacles by enabling the direct creation of devices from a digital design, eliminating the need for complex tooling and mold fabrication.
Researchers can now rapidly adapt, test, and individualize prototypes – a significant boost to innovation in the field of soft robotics. The team demonstrated the capabilities of the technique with several prototypes, including an actuator resembling a flower that unfolds its spirally printed petals when pressurized, and a five-fingered gripper with articulated knuckles capable of securely grasping objects. Both were produced in a single, uninterrupted printing process, requiring no post-assembly.
The complexity of the movement is programmed solely through the orientation of the two materials within the filament. This simplification of the manufacturing process is expected to be a game-changer for the practical application of soft robots, which are valued for their safety and adaptability in interacting with humans and delicate objects.
Potential applications highlighted by the researchers include the rapid production of components for minimally invasive surgical tools, enabling safer navigation within the body, and the creation of customized grippers and actuators for handling sensitive products in industrial automation. The technology also holds promise for the development of more comfortable and dynamically adaptable assistive devices and exoskeletons.
“By removing the high barrier to complex fabrication, we can enable more labs and companies to develop specialized soft robots,” the researchers stated. The team is currently focused on refining the process and exploring new material combinations, opening up a new design space for the next generation of intelligent, flexible robots. Recent advancements in 3D printing, as reported by VoxelMatters, highlight Harvard’s Lewis Lab’s continued innovation in this area, including further development of helical printing methods.