Researchers at the University of Illinois at Champaign in the United States used the spinal cord segment of rats to create tiny biological robots that can make walking movements. The tiny robot developed by the researchers, known as a spin robot, is powered by rat muscleand and spinal cord tissue on a soft 3D-printed hydrogel skeleton.
The team said that integrating the rat’s spinal cord gave the spin robot a more natural walking rhythm. Research leader Martha Gillett says spin robots are the beginning of interactive biological devices that could be used in medicine and neurocomputing. The spin robot’s construction process began with researchers printing a small skeleton in 3D, consisting of two columns of legs and a flexible back bone, the entire skeleton is only a few millimeters wide.
The team then planted muscle cells on the skeleton, allowing them to grow into muscle tissue. The final part is the integration of a lumbar spinal cord from rats. The researchers specifically chose the lower back spinal cord, which previous studies have shown that the lumbar spinal cord holds the neural circuits that alternate around the movement of the controlled limb.
Part of the research team’s research included devising a way to extract the complete spinal cord and combine it with a biorobot to grow muscle and nerve tissue together. They must also do all this work by forming a connection between neurons and muscles. The team said the researchers saw spontaneous muscle contractions in spin robots, suggesting that the required neural muscle connections had formed signals.
Later, scientists demonstrated the function of the spinal cord to promote walking by adding glutamate, a neurotransmitter that causes nerve cells to signal and cause muscles to contract. The result is that the legs move at a natural walking pace, and when glutamate is washed away, the rotating robot stops walking. The researchers then plan to further refine the movements of small robots to make their gait more natural. The team hopes their breakthrough will allow researchers to study neurodegenerative diseases such as ALS in real time.