To demonstrate their finding, the researchers designed hydraulically-powered robot bodies, requiring no assembly after printing. They hope the new printing strategy could yield much simpler robot mechanics, requiring minimal assembly and tooling to only integrate basic motor and battery blocks.
The novel 3D printing strategy call for multiple ink-jet nozzles, one for the UV-curable photopolymer (which will become the solid), and one for a non-curable liquid. The main hurdle was to figure out workable printing patterns (with find droplet resolutions of 20 to 30 microns) that would allow the liquid and the UV-curable resin to stand side by side without coalescing or collapsing through wetting interactions. The result was the 3D printing of complex pre-filled fluidic channels. Using soft rubber for the solid material, the researchers demonstrated their ‘printable hydraulics’ concept by 3-D printing a tiny six-legged robot that can crawl via 12 hydraulic pumps embedded within its body (all 12 pumps moved by a unique crankshaft driven by a single external motor with a battery).
Among the robot’s key parts are several set of accordion-like “bellows” that are 3-D printed directly into its body. To propel the robot, the bellows uses fluid pressure that is then translated into a mechanical force. Other robotic parts demonstrated include a soft rubber gripper and a gear pump that can produce continuous fluid flow (as an alternative to the bellows).
Visit the MIT at www.mit.edu