Tiny Spinobots Use Rat Spinal Cords To Walk

Researchers at the University of Illinois at Urbana-Champaign have created tiny biological robots that can make walking motions thanks to rat spinal cord segments. The tiny robots that the researchers developed called spinobots and are powered by rat muscle and spinal cord tissue on a soft 3D printing hydrogel skeleton. Past generations of the biological robots were able to move forward by simple muscle contraction.The team says that integrating the rat spinal cord gives the spinobots a more natural walking rhythm. Study lead Martha Gillett says that the spinobots are the beginnings of interactive biological devices that could have applications in medicine and neurocomputing. The construction process for the spinobots starts with the researchers 3D printing a tiny skeleton consisting of two posts for legs and a flexible backbone with the entire skeleton only a few millimeters across.

The team then seeded the skeleton with muscle cells, which grew into muscle tissue. The last part of the process was to integrate a segment of the lumbar spinal cord from a rat. The researchers selected the lumbar spinal cord specifically because previous research demonstrated that it houses the circuits that control left-right alternation for lower limbs during walking.

Part of the team's research included devising a way to extract the intact spinal cord and culture it along with integrating it into the bio-bot and culturing the muscle and nerve tissue together. They also had to do all of that work in a way that the neurons form junctions with the muscle. The team said that the researchers saw spontaneous muscle contraction in the spinobots, signaling that the desired neuromuscular junctions had formed.

The scientists later verified the spinal cord is functioning to promote walking by adding glutamate, a neurotransmitter that prompts nerve cells to signal the muscle to contract. The result was that the legs moved in a natural walking rhythm, and when the glutamate was rinsed away, the spinobots stopped walking. The researchers next plan to refine the movements of the tiny robots further to make their gaits more natural. The team hopes that their breakthrough could allow researchers to study neurodegenerative diseases such as ALS in real-time.