A 3D-printing method using “printable hydraulics,” which combines liquid and solid materials, can produce functional robots, according to a new paper from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), released today.

“All you have to do is stick in a battery and motor, and you have a robot that can practically walk right out of the printer,” said CSAIL Director Daniela Rus.

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MIT’s work, which was funded in part by a grant from the National Science Foundation, shows how current 3D printers can be used to produce a tiny six-legged robot, weighing about 1.5 pounds and less than six inches long. (Here’s a little more on how they got the 3D printer to do this.) The tiny robots are motor-operated, and can crawl with a DC motor that uses 12 hydraulic bellows to pump fluid into the robot’s legs. And, aside from its motor and battery, these small robots are created with no assembly required. Here’s a video of how it works.

MIT’s 3D printing method was also used to make soft parts, like grippers, for the robot Baxter, a small robot from Rethink Robotics–which has been a fundamental challenge in robotics.

Here are the other important features of MIT’s 3D-printed robots, according to the release:

  • The printing method is compatible with any multi-material 3D inkjet printer.
  • Printable hydraulics uses an inkjet printer in a layer-by-layer process, which includes depositing different materials and using a “high-intensity UV light to solidify all of the materials (minus, of course, the liquids).”
  • Each layer consists of a photopolymer, which is a solid, and a non-curing material, which is a liquid.
  • The design template is customizable, and can create robots of different sizes, shapes, and functions.
  • Print time is 22 hours.

CSAIL’s team told TechRepublic that they foresee many advantages of the system, including disaster relief in dangerous environments. Nuclear sites, they said, “need to be remediated to reduce their radiation levels. Unfortunately, the sites are not just lethal to humans, but radioactive enough to destroy conventional electronics.”

“Printable robots like these can be quickly, cheaply fabricated, with fewer electronic components than traditional robots,” said Robert MacCurdy, part of MIT’s team behind the solution.

“If you have a crawling robot that you want to have step over something larger, you can tweak the design in a matter of minutes,” MacCurdy said. “In the future, the system will hardly need any human input at all–you can just press a few buttons, and it will automatically make the changes.”

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Joe Jones, original creator of the Roomba and founder of Franklin Robotics, looks forward to this new tool for building robots, and sees the solid/liquid printing as an “exciting development.”

But while he is encouraged by CSAIL’s work, he adds a note of caution, seeing the development as “a breakthrough in 3D printing, but an incremental step in robotics.”

An impediment, he said, is “the challenge of making robots inexpensive enough to compete with non-robotic solutions.” In agriculture or warehousing, for example, manual labor or automation may be more cost-effective than building individual robots.

At this point, Jones said, there doesn’t exist “any single advance that can fundamentally change the situation.”