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Sensor brings epileptic brain into focus

NYU / U. ILLINOIS / U. PENN (US) — A flexible sensor is expected to offer unprecedented views of brain activity during epileptic seizures—as much as 400 times current levels—with minimal wiring.

Prior to the new technology, tapping into the human brain to understand its functions in daily life—as well as its malfunctions in illness—was challenging because of unwieldy, invasive arrays of electrodes and sensors that can damage tissue while only reading activity in a limited area. The need to wire each individual sensor at the electrode-tissue interface resulted in a mass of cumbersome leads rendering a high-resolution map of large areas logistically impossible.

Jonathan Viventi, assistant professor at the Polytechnic Institute of New York University (NYU-Poly), and colleagues devised a streamlined, implantable electrode array integrating ultrathin, flexible silicon transistors capable of sampling large areas of the brain with limited use of wires.


Jonathan Viventi (Credit: Ardis Kadiu, NYU-Poly)

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Reported in the November issue of Nature Neuroscience, the new approach allows dense arrays of thousands of multiplexed sensors that provide unprecedented—and minimally invasive—spatial resolution.

In experiments, just 39 wires were required for 360 electrodes. The design can be readily scaled to thousands of electrodes, while maintaining a small number of wires. The arrays are also non-penetrating and, unlike current techniques, cause little or no damage to fragile brain tissue. The use of flexible silicon also allows active circuitry to be built right at the brain surface.

“The circuits we’re familiar with are built on rigid silicon, which doesn’t conform to the body,” Viventi says. “Ultrathin silicon retains its performance while being flexible, and is much better suited to implantable devices. It’s the difference between a piece of paper and a piece of 2×4 lumber—same material, dramatically different properties.”

In experiments, researchers used their system to record various types of brain activity in animals, including sleep and visual responses and observation of the brain during an epileptic seizure. The techniques may improve understanding of what causes epilepsy and lead to implantable technologies to stop or prevent seizures in patients.

The scientists believe this is the first reported use of ultrathin, flexible silicon in a brain interface device and say the research holds promise for other medical applications, including improvements of existing implantable devices including cardiac pacemakers and defibrillators, cochlear and retinal implants, and motor prosthetic systems.

The longer-term goal is to configure these implantable arrays for use anywhere in the body, equipped with wirelessly controlled sensors capable of multiple functions such as recording, stimulating, and ablating.

Co-authors include senior author Brian Litt of the University of Pennsylvania and John Rogers of the University of Illinois at Urbana-Champaign. The research received support from the National Institutes of Health, the National Science Foundation; the U.S. Department of Energy Division of Materials Sciences; Citizens United for Research in Epilepsy; and the Dr. Michel and Mrs. Anna Mirowski Discovery Fund for Epilepsy Research.

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