Neural electrodes must work for time periods ranging from hours to years. When the electrodes are implanted, the brain first reacts to the acute injury with an inflammatory response. Then the brain settles into a wound-healing, or chronic, response.
It's during this secondary response that brain tissue starts to encapsulate the electrode, cutting it off from communication with surrounding neurons.
The new brain implants developed at U-M are coated with nanotubes made of poly(3,4-ethylenedioxythiophene) (PEDOT), a biocompatible and electrically conductive polymer that has been shown to record neural signals better than conventional metal electrodes.
U-M researchers found that PEDOT nanotubes enhanced high-quality unit activity (signal-to-noise ratio >4) about 30 percent more than the uncoated sites. They also found that based on in vivo impedance data, PEDOT nanotubes might be used as a novel method for biosensing to indicate the transition between acute and chronic responses in brain tissue.
The results are featured in the cover article of the Oct. 5 issue of the journal Advanced Materials. The paper is titled, "Interfacing Conducting Polymer Nanotubes with the Central Nervous System: Chronic Neural Recording using Poly(3-4-ethylenedioxythiophene) Nanotubes."
"Microelectrodes implanted in the brain are increasingly being used to treat neurological disorders," said Mohammad Reza Abidian, a post-doctoral researcher working with Professor Daryl Kipke in the Neural Engineering Laboratory at the U-M Department of Biomedical Engineering.
"Moreover, these electrodes enable neuroprosthetic devices, which hold the promise to return functionality to individuals with spinal cord injuries and neurodegenerative diseases. However, robust and reliable chronic application of neural electrodes remains a challenge."
In the experiment, the researchers implanted two neural microelectrodes in the brains of three rats. PEDOT nanotubes were fabricated on the surface of every other recording site by using a nanofiber templating method. Over the course of seven weeks, researchers monitored the electrical impedance of the recording sites and measured the quality of recording signals.
PEDOT nanotubes in the coating enable the electrodes to operate with less electrical resistance than current metal electrode sites, which means they can communicate more clearly with individual neurons.
"Conducting polymers are biocompatible and have both electronic and ionic conductivity," Abidian said. "Therefore, these materials are good candidates for biomedical applications such as neural interfaces, biosensors and drug delivery systems."
In the experiments, the Michigan researchers applied PEDOT nanotubes to microelectrodes provided by the U-M Center for Neural Communication Technology. The PEDOT nanotube coatings were developed in the laboratory of David C. Martin, now an adjunct professor of materials science and engineering, macromolecular science and engineering, and biomedical engineering. Martin is currently the Karl W. Böer Professor and Chair of the Materials Science and Engineering Department at the University of Delaware.
Martin is also co-founder and chief scientific officer for Biotectix, a U-M spinoff company located in Ann Arbor. The company is working to commercialize conducting polymer-based coatings for a variety of biomedical devices
In previous experiments, Abidian and his colleagues have shown that PEDOT nanotubes could carry with them drugs to prevent encapsulation.
"This study paves the way for smart recording electrodes that can deliver drugs to alleviate the immune response of encapsulation," Abidian said.
The research is funded by the Army Research Office, Center for Neural Communication Technology and National Institutes of Health.
Full text of article: http://www3.interscience.wiley.com/cgi-bin/fulltext/122525755/PDFSTART
High-resolution illustration: http://umich.edu/news/index_nr.html?Releases/2009/Sep09/brain
Mohammad Reza Abidian: http://www-personal.umich.edu/~mabidian/
The University of Michigan's College of Engineering is ranked among the top engineering schools in the country. At more than $130 million annually, its engineering research budget is one of the largest of any public university. Michigan Engineering is home to 11 academic departments and a National Science Foundation Engineering Research Center. The college plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world-class Lurie Nanofabrication Facility. Michigan Engineering's premier scholarship, international scale and multidisciplinary scope combine to create the Michigan Difference.
Byron Roberts | Newswise Science News
Study tracks inner workings of the brain with new biosensor
16.08.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn
Foods of the future
15.08.2018 | Georg-August-Universität Göttingen
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences