Rat Spines Power Robots With 3D-Printed Muscles

A team of scientists used part of a rat spine to control robot legs with 3D-printed muscles grown in a lab from mouse cells, reports New Scientist.

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Rat spines control 3D-printed mouse muscles

Robots made with live rat spines might help the study of diseases as they move through biological tissues, eventually leading to a biological prosthetics, New Scientist reports.

Collin Kaufman, together with his colleagues at the University of Illinois at Urbana-Champaign, built biological robots with 3D-printed muscles composed of the lab-grown cells of mice. But without the rat spine, the muscles can't exert force in concert — that requires some kind of central nervous system.

This is why, instead of attaching the 3D-printed muscles to an electrical control system, the researchers decided to employ the part of a rat spine that controls hind legs (in a living rat). Once attached to muscles, the spine extended neurons into them and sent electrical signals that coursed through the muscles, causing them to contract.

Flexing 3D printed muscles

The muscles were connected to the spine via a flexible scaffold with two arms sticking out perpendicular to the spine — allowing the scaffold to flex when muscles contract — so the arms point toward one another.

"The spinal cord is able to recognize these muscles and do what it does in the body — create these rhythmic contractions — after being out of the body for more than a week," said Kaufman, to New Scientist. Contractions were controlled with more or fewer neurotransmitters installed in the system.

Studying neurological disease in real-time

It's difficult to study spinal neurons — which comprise the peripheral nervous system — in live animals. This is why it's also hard to study diseases that affect them, like amyotrophic lateral sclerosis (ALS), also called motor neurone disease. Novel systems like this might make it less difficult to study how these diseases progress in real-time, according to Kaufman, reports New Scientist.

At roughly 6 millimeters long, it'd be hard to make these robots larger because of the difficulty moving nutrients to all of the living tissue. However, once we discover ways to make them bigger, they might see applications in other medical arenas.

"Eventually, something like this could be used for prosthetics," said Kaufman to New Scientist. But this would likely be done with lab-born tissues, instead of rat spines, he added. "Nobody will have scary rat-spine hands."