image: Rice University neuroscientist Chong Xie leads a team that has won a $2.9 million grant from the NIH to develop a state-of-the-art implantable neural electrode system.
Credit: (Photo by Jeff Fitlow/Rice University)
HOUSTON – (July 17, 2024) – Rice University neural engineer Chong Xie and his team have won a $2.9 million R01 grant from the National Institutes of Health to develop a state-of-the-art implantable neural electrode system that is highly biocompatible, untethered and capable of stable, long-term and large-scale neural recording and stimulation.
“We aim to significantly advance our understanding of neural circuits by providing a tool that can seamlessly integrate with neural tissue, record at cellular and millisecond resolutions and maintain functionality over long periods,” said Xie, associate professor of electrical and computer engineering and bioengineering and a member of the Rice Neuroengineering Initiative.
The project builds on previous work in Xie’s Nanoscale Neural Interface Laboratory at Rice, which has pioneered the development of ultraflexible nanoelectronic thread probes (NETs). NETs can be as thin as 1 micrometer and very flexible, making them highly compatible with neural tissue. Prior research has shown that NETs produced no observable tissue damage or scarring and that they are capable of tracking populations of neurons in the brains of mice and rats over many months.
“Neural electrodes have been a very powerful tool in neuroscience research, and recently they have also become more useful in clinical applications,” Xie said. “A decade ago, neural electrodes were quite invasive. Using a combination of material and structure, we developed a device that gets along with nervous tissue very well and functions very robustly.”
Over the past few years, Xie and his team have worked on optimizing NETs and applied the devices in many different animal models, showing their potential utility in a wide range of projects, including stroke recovery, aging, regenerative medicine, vision, memory and learning as well as spinal cord research.
Now the researchers aim to improve the resolution of the probe by increasing the density of the neurons sampled.
“Neurons are very densely packed in the brain, and that density is fairly uniform across the cortex,” Xie said. “Inside brain tissue, if you go 20-30 micrometers in any direction, you run into a neuron. With our initial NETs, we had no more than 64 channels along a distance of a few millimeters. There are 1,000 micrometers in 1 millimeter, so we were able to interface with far fewer neurons along those depths than what we would like, which is to record or interface with every neuron along the distance, every neuron we can touch with this device.”
Among the most significant limiting factors to improving the probe system are the fabrication resolution and the backend device that amplifies and digitizes the signals collected by NETs. To address the former, the researchers collected preliminary data on a new fabrication method: electron-beam lithography.
“We use electron beams to define the features we have in these devices,” Xie said. “That allows us to go much higher in terms of spatial resolution. Basically, instead of writing 10 lines, we can now write over 100 lines, so that we can pack more than 10 times more channels within the same device size. That will allow us to improve the recording and simulation capacity dramatically.”
In addition to optimizing the probes, Xie and collaborators will work on integrating the NETs with implantable electronics and assess their performance over time. Addressing backend challenges, the team will develop an application-specific integrated circuit, or ASIC chip, as well as systems for wireless power transfer and data transmission, enabling fully untethered operation of the neural recording devices.
Another project aim is to collect a comprehensive neural recording dataset and perform a thorough characterization, tracking the same neuron populations in order to delineate changes in neural activity occurring either due to biophysical causes or circuitry.
“This effort aims to enhance our understanding of chronic electrophysiology and pave the way for powerful applications of stable large-scale neural electrodes in neuroscience,” Xie said.
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This news release can be found online at news.rice.edu.
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Award information:
Title: “A Nanoelectronic Strategy for Reliable, Large-scale Chronic Neural Recording”
Award number: 2R01NS102917-06
Link: https://reporter.nih.gov/search/zzqqKvW-0kGVcLUc0PCuNA/project-details/10883380
Image downloads:
https://news-network.rice.edu/news/files/2024/07/240520_Cell_Fitlow_0478-copy.jpeg
CAPTION: Rice University neuroscientist Chong Xie leads a team that has won a $2.9 million grant from the NIH to develop a state-of-the-art implantable neural electrode system. (Photo by Jeff Fitlow/Rice University)
https://news-network.rice.edu/news/files/2024/07/0724_Xie_NIH_grant.jpg
CAPTION: NETs can be as thin as 1 micrometer and very flexible, making them highly compatible with neural tissue. (Photo by Jeff Fitlow/Rice University)
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