Understanding the neural interface within the brain is critical to understanding aging, learning, disease progression, and more. However, current approaches to studying neurons in animal brains to better understand human brains all carry limitations, from being highly invasive to not discovering enough information. A newly developed pop-up electrode device could gather more in-depth information about individual neurons and their interactions with each other while reducing the potential for brain tissue damage.
The researchers, led by Huanyu “Larry” Cheng and James L. Henderson, assistant professor of engineering sciences and mechanics in the College of Engineering, published their results in npj flexible electronics.
“It’s a challenge to understand the connection between the large number of neurons within the brain,” Cheng said. “In the past, people have developed a device that is placed directly on the cerebral cortex to detect information on the surface layer, which is less invasive. But without inserting the device into the brain, it is more difficult to detect information between the cortex.”
In response to this limitation, researchers have developed probe-based electrodes that are inserted into the brain. The problem with this method is that it is not possible to obtain a 3D mapping of neurons and brain without doing multiple probes, which are difficult to place on a flexible surface and would be very harmful to brain tissue.
“To address this problem, we use pop-up design,” Cheng said. “We can fabricate sensor electrodes with similar precision and performance to current fabrication. But at the same time, we can insert them into 3D geometry before inserting them into the brain. It’s like a pop-up children’s book: you have a flat shape, and then you apply a compressive force. It transforms 2D into 3D.” It provides a 3D device with performance similar to that of 2D.”
The researchers said that in addition to the unique design that pops up in three dimensions after being inserted into the brain, their device also uses a combination of materials that have not been used in this particular way before. Specifically, they used polyethylene glycol, a material that had been used before, as a biocompatible coating to create the rigidity, which is not the purpose for which it was used previously.
“For the device to be inserted into the brain, it must be rigid, but after the device is in the brain, it must be flexible,” said co-author Ki Jun Yu of Yonsei University in the Republic of Korea. “So we used a biodegradable coating that provides a tough outer layer on the device. Once the device is in the brain, that hard coating degrades, restoring the initial flexibility. And by combining the material structure and engineering of this device, we’ll be able to take input from the brain to study connectivity. three-dimensional neurons.”
The research’s next steps include iteration of the design to make it useful not only for gaining a better understanding of the brain but also for surgeries and disease treatments.
“In addition to animal studies, some applications of device use could be operations or disease treatments where you may not need to take the device out, but you certainly want to make sure that the device is biocompatible over a long period of time,” Cheng said. “It is useful to design the structure.” To be as small, soft, and porous as possible so that brain tissue can penetrate and be able to use the device as a scaffold to grow on top of that, resulting in a much better recovery. We may also want to use a biodegradable material that can be dissolved after use.”
Other contributors are: Jo Young Lee, Sang Hoon Park, Eugene Kim, Young Ok Cho, Jaejin Park, Jung Hoon Hong, Kyobin Kim, Jongwon Shin, Jeong Eun Joo, In Sikmin and Mingyu Sang from Yonsei University of the Republic. Korea. Hyogyun Shin, Ui Jin Jeong, Aizan Zumbaeva, Kyung Yun Kim, Eun Bin Hong, Min Ho Nam, Hojung Geun, and Yongmi Jung from the Korea Institute of Science and Technology in the Republic of Korea; Il-Joo Cho from Korea University in the Republic of Korea; and Yuyan Zhao and Bowen Li of the Department of Engineering Sciences and Mechanics at Penn State.
The Korea Nation Research Foundation and the National Institutes of Health funded this research.