A schematic of the hydrogel hybrid brain-machine interface. Image: KAIST.
A schematic of the hydrogel hybrid brain-machine interface. Image: KAIST.

Researchers at the Korea Advanced Institute of Science and Technology (KAIST), together with collaborators in the US, have unveiled a newly developed hydrogel-based flexible brain-machine interface, which they report in a paper in Nature Communications.

To study the structure of the brain or to identify and treat neurological diseases, it is crucial to develop an interface that can stimulate the brain and detect its signals in real time. However, existing neural interfaces are mechanically and chemically different from real brain tissue, and so instigate a foreign body response that leads to the formation of an insulating layer (glial scar) around the interface, which shortens its lifespan.

To solve this problem, the research team of Seongjun Park at KAIST developed a 'brain-mimicking interface' by inserting a custom-made multifunctional fiber bundle into the body of a hydrogel. Not only does this interface contain an optical fiber that can control specific nerve cells with light to perform optogenetic procedures, but it also has an electrode bundle to read brain signals and a microfluidic channel to deliver drugs to the brain.

The interface is easy to insert into the body when the hydrogel is dry, as it is solid at this point. But once in the body, the hydrogel quickly absorbs body fluids, allowing it to mimic the properties of the surrounding tissues, thereby minimizing the foreign body response.

The research team applied this interface to animal models, and showed that it was possible to detect neural signals for up to six months, which is far beyond what had previously been recorded. The team also found that it was possible to use the interface to conduct long-term optogenetic and behavioral experiments on freely moving mice, with a significant reduction in foreign body responses such as glial and immunological activation compared to existing interfaces.

"This research is significant in that it was the first to utilize a hydrogel as part of a multifunctional neural interface probe, which increased its lifespan dramatically," said Park. "With our discovery, we look forward to advancements in research on neurological disorders like Alzheimer's or Parkinson's disease that require long-term observation."

This story is adapted from material from KAIST, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.