Smart Prosthetics Exploring Assistive Devices for the Body and Mind: Task Group Summaries (2007) / Chapter Skim
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Brain Interfacing with Materials: Recording and Stimulation Electrodes
Brain Interfacing with Materials: Recording and Stimulation Electrodes
Pages 31-44
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From page 31... ...
A cylinder with a radius 150 µm contains up to 1000 neurons in the cortex. The use of two or more recording sites allows for the triangulation of the position of the neurons because the amplitude of the recorded spike is a function of the distance between the neuron and the electrode.
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From page 32... ...
Extraction of the "neuronal code." In addition to increasing the numbers of recording sites, on-chip amplification, filtering, and time-division multiplexing will dramatically decrease the number of wires between the brain and electronic equipment by directly feeding the multiplexed digital signal into a computer processor. Programmed microstimulation through the recording sites and potentially real-time signal processing will not only facilitate basic research but is also a prerequisite for efficient, fully implantable neural prosthetic devices.
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From page 33... ...
Please be sure to review the second write-up, which immediately follows this one.) Summary written by: Megan Chao, Graduate Student in Broadcast Journalism, Annenberg School for Communication, University of Southern California Task group members: • Ravi Bellamkonda, Professor, Biomedical Engineering, Georgia Institute of Technology • Megan Chao, Graduate Student in Broadcast Journalism, Annenberg School for Communication, University of Southern California • Elias Greenbaum, Corporate Fellow, Chemical Sciences Division, Oak Ridge National Laboratory • William Hammack, Professor, Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign • Kendall Lee, Assistant Professor of Neurosurgery, Physiology, and Biomedical Engineering, Neurosurgery Department, Mayo Clinic, Rochester • Pedram Mohseni, Assistant Professor, Electrical Engineering and Computer Science, Case Western Reserve University • Vivian Mushahwar, Assistant Professor and AHFMR Scholar, Biomedical Engineering and Center for Neuroscience, University of Alberta • Richard Normann, Professor, Bioengineering Department, University of Utah • Matthew O'Donnell, Dean, College of Engineering, University of Washington • Joseph Pancrazio, Program Director, Repair and Plasticity Cluster Department, Division of Extramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health
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From page 34... ...
Working group members identified the following as a major challenge for brain interfacing with materials: creation of penetrating electrode arrays that can reliably record or stimulate neuronal activity for longer than one year without jeopardizing the biocompatibility of the implant. Mechanisms of Electrode Failure Understanding the importance of electrode arrays in neuroprosthetic applications first requires recognition of the mechanisms of electrode failure.
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From page 35... ...
The formation of scar tissue around an electrode array unquestionably contributes to the failure of the electrode in its ability to accurately collect and transmit neuronal signals. Scarring is a result of the body's natural wound repair process, occurring as a result of implantation, and the physiology of scar tissue may make for diminished electrode functionality.
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From page 36... ...
The smaller size of the electrode inherently reduces implantation risks, but achieving electrical interfaces become an issue. Group member Pedram Mohseni suggested wireless interfacing, as the technology is highly prevalent in today's society.
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From page 37... ...
Continuing from the earlier discussion about what constitutes "smart," group members brainstormed examples of smart interfaces including encapsulating materials that react to emerging scar formation, the autopositioning of individual electrodes for optimizing signal acquisition, and microfluidics for injecting materials to make the tissue more permissive. Interdisciplinary research in smart prosthetics will essentially evolve better devices and systems for improvement in the quality of life.
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From page 38... ...
Summary written by: Edyta Zielinska, Graduate Science Writing Student, New York University Task group members: • Orlando Auciello, Materials Science Department, Argonne National Laboratory
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From page 39... ...
Army Research Office • Bruce C Wheeler, Professor and Interim Head, Bioengineering Department, University of Illinois • Edyta Zielinska, Graduate Science Writing Student, New York University Summary Using technology to restore lost functions of hearing, vision, movement, scientists are working to make reality out of what was once considered within the realm of miracles.
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From page 40... ...
. Longer lasting brain electrodes could also improve the electrical brain stimulation systems, like those used to relieve the tremors of Parkinson's disease, as well as electrodes that pick up the brain's signals and help paralyzed patients control electronic devices just by thinking.
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From page 41... ...
While it was unclear whether the scarring caused by the brain's reaction caused the failure, there was agreement that this space between the neurons and the electrode would somehow need to be bridged. Another issue was what Martin called, "the fork in the Jell-O problem." The microscopic wiggling of a hard metallic device against the mushy brain tissue could either change the position of the electrode, or cause continual inflammation in the area.
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From page 42... ...
Perhaps the surface of the electrode could be engineered in such a way to improve the electrical and mechanical interactions with the tissue, either by using stem cells or genetically engineered cells. "We could make these cells sniffers," said de Groat, using tissue engineering to create biological wires that would seek out and communicate with the surrounding neurons.
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From page 43... ...
43 BRAIN INTERFACING WITH MATERIALS people who talk like this," said Kyriakides. Many other group members echoed the sentiment.
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