Sci-fi films and video games for years have dreamed up humanoids with super strength who could make our lives just a little bit easier. Making that a reality hasn’t been so easy.

Now, a group of researchers at Columbia University have gotten us a step closer to the robots in our imaginations. The 3-D-printed muscle meant for soft, fleshy robots can lift 1,000 times its own weight and exert three times more force than human muscles.

“We’ve been making great strides toward making robot minds, but robot bodies are still primitive,” Hod Lipson, a mechanical engineering professor at Columbia University, said in a release. “This is a big piece of the puzzle.”

Why soft muscles matter

The most useful robots will probably need the ability to lift, push and pull considerable weight — and they need bodies that are nimble enough to move like humans while they do it.

Then there’s the safety aspect of “soft robotics”: Squishy materials like these muscles help pave the way for fleshy robots. That material allows scientists to create robo-companions whose bodies aren’t rigid and dangerous (imagine accidentally getting jabbed by a metal arm, for example).

“You cannot work with a lot of robots today, side-by-side, because of the safety,” Aslan Miriyev, a postdoctoral researcher at Columbia University’s Creative Machines lab, said by phone. “The robot will do what it will do — and it’ll do it perfectly — but it won’t care about you. In some labs, you cannot just enter because you will actually be injured by those robots.”

Here’s how they work

These soft muscles are a step toward creating the perfect humanoid — one that we could someday see helping us take out the trash or move into our new apartments.

But robot muscles need to be able to expand and contract like a balloon as they work, sort of like human muscles do.

“These are pretty heavy — literally heavy — and big pieces of equipment that limit miniaturization,” Miriyev said. “In our case, we didn’t need any external equipment — just 8 to 30 volts of electricity, depending on the size of the muscle, and that’s it.”

The synthetic muscle is electrically actuated (expanded) using thin wires in a rest position. Aslan Miriyev/Columbia Engineering

The 3-D-printed soft muscle is basically modeled after human and animal muscles, and the materials are incredibly cheap: Outside of small lab quantities, Miriyev expects it to cost less than 3 cents per gram. He said he hopes it will help develop more realistic and capable soft robots, particularly to help out with health care. He said he imagines these robots providing assistance out in the field after natural disasters, like the recent earthquake that has devastated Mexico, or in actual hospitals as an extra set of hands.

“Imagine nurses, who are under high pressure today because of low nurse-to-patient ratios: They can get help with specific procedures around the hospital,” Miriyev said. “For me, achieving that would already be a great investment of my time and career — all of the effort it takes to build this muscle.”