This rendering of the ultraflexible probe in neural tissue gives viewers a sense of the device’s tiny size and footprint in the brain. Rendering courtesy of Science Advances.
Engineering researchers at The University of Texas at Austin (UT Austin) have designed ultraflexible, nanoelectronic-thread brain probes that can achieve more reliable long-term neural recording than existing probes and don’t elicit scar formation when implanted. There is a growing interest in developing long-term tracking of individual neurons for neural interface applications, such as extracting neural-control signals for people with amputations to control high-performance prostheses. It also opens possibilities to follow the progression of neurovascular and neurodegenerative diseases such as stroke, Parkinson’s, and Alzheimer’s. The researchers describe their findings in a research article published on February 15 in Science Advances.
One of the problems with conventional probes is that their size and mechanical stiffness frequently cause damage around the tissue they encompass. Additionally, while it is possible for the conventional electrodes to record brain activity for months, they often provide unreliable and degrading recordings. It is also challenging for conventional electrodes to electrophysiologically track individual neurons for more than a few days.
In contrast, the UT Austin team’s electrodes have mechanical compliances approaching that of brain tissue and are more than 1,000 times more flexible than other neural probes. This ultraflexibility leads to an improved ability to reliably record and track the electrical activity of individual neurons for long periods of time, and they comply with the microscale movements of tissue and still stay in place. The probe’s size also drastically reduces the tissue displacement, so the brain interface is more stable, and the readings are more reliable for longer periods of time. To the researchers’ knowledge, the UT Austin probe-which has a cross-section that is only a fraction of that of a neuron or blood capillary-is the smallest among all neural probes.
In experiments in mouse models, the researchers found that the probe’s flexibility and size prevented the agitation of glial cells, which is the normal biological reaction to a foreign body and leads to scarring and neuronal loss.
Editor’s note: This story was adapted from materials provided by UT Austin.
