Glassy carbon electrodes advances brain-computer interface technology

The Center for Sensorimotor Neural Engineering-a collaboration of San Diego State University with the University of Washington and the Massachusetts Institute of Technology is working on an implantable brain chip that can record neural electrical signals and transmit them to receivers in the limb. Results of the research study utilizing above technology are published in the journal Nature Scientific Reports.

Glassy Carbon Electrodes for Brain-computer Interface technology
This image shows a sheet of glassy carbon electrodes patterned inside chips.
Credit: Sam Kassegne, San Diego State University.

When people suffer spinal cord injuries and lose mobility in their limbs, the brain can still send clear electrical impulses and the limbs can still receive them, but the signal gets lost in the damaged spinal cord. The brain chip the researchers works by bypassing the damage and restoring movement.

The technology, known as a brain-computer interface, records and transmits signals through electrodes, which are tiny pieces of material that read signals from brain chemicals known as neurotransmitters. The device works by recording and analyzing brain signals and convert them into a relevant electrical signal pattern, these signals are then transmitted to the limb’s nerves, or even to a prosthetic limb, restoring mobility and motor function.

The current state-of-the-art material for electrodes in these devices is thin-film platinum. The problem is that these electrodes can fracture and fall apart over time, said one of the study’s lead investigators, Sam Kassegne, deputy director for the CSNE at SDSU and a professor in the mechanical engineering department. To overcome this problem researchers developed electrodes made out of glassy carbon, a form of carbon. This material is about 10 times smoother than granular thin-film platinum, meaning it corrodes less easily under electrical stimulation and lasts much longer than platinum or other metal electrodes. Researchers are using these new and improved brain-computer interfaces to record neural signals both along the brain’s cortical surface and from inside the brain at the same time.

A doctoral graduate student in Kassegne’s lab, Mieko Hirabayashi, is exploring a slightly different application of this technology. She’s working with rats to find out whether precisely calibrated electrical stimulation using these electrodes can cause new neural growth within the spinal cord with hope to replicate these results in humans. The new glassy carbon electrodes will allow her to stimulate, read the electrical signals of and detect the presence of neurotransmitters in the spinal cord better than ever before.

Citation: Vomero, Maria, Elisa Castagnola, Francesca Ciarpella, Emma Maggiolini, Noah Goshi, Elena Zucchini, Stefano Carli, Luciano Fadiga, Sam Kassegne, and Davide Ricci. “Highly Stable Glassy Carbon Interfaces for Long-Term Neural Stimulation and Low-Noise Recording of Brain Activity.” Scientific Reports 7 (2017): 40332.
Research funding: National Science Foundation.
Adapted from press release by San Diego State University.

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