Flexible Sensors Offer Unprecedented View of Brain Activity During Epileptic Seizures

Tapping into the human brain to understand its functions in daily life — as well as its malfunctions in illness — has long been a challenge for researchers. Mapping brain activity requires unwieldy, invasive arrays of electrodes and sensors that can damage tissue while only reading activity in a limited area.

Jonathan Viventi, assistant professor at the Polytechnic Institute of New York University (NYU-Poly) and New York University (NYU), co-led a team of researchers to devise a streamlined, minimally invasive brain interface that may yield new insights into the causes of brain diseases like epilepsy, as well as usher in a new generation of implantable neuroprosthetic and diagnostic devices. 

At the core of the research is a novel, implantable electrode array integrating ultrathin, flexible silicon transistors capable of sampling large areas of the brain with minimal wiring.

The findings are published in the December issue of Nature Neuroscience. Co-authors include the study’s senior author Brian Litt of the University of Pennsylvania and John Rogers of the University of Illinois at Urbana-Champaign. The technology has been licensed to mc10, a Boston-area company delivering flexible electronics for industrial and biomedical applications. 

Current efforts to record or stimulate brain activity are limited by the need to wire each individual sensor at the electrode-tissue interface. The resulting mass of leads is cumbersome and renders a high-resolution map of large areas logistically impossible. 

This new approach enables dense arrays of thousands of multiplexed sensors that provide unprecedented spatial resolution — more than 400 times the current level — with a fraction of the wires. 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. 

Viventi explains that "the circuits we're familiar with are built on rigid silicon, which doesn't conform to the body. 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 2x4 lumber — same material, dramatically different properties."

In experiments, the research team deployed 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. Their techniques may improve understanding of what causes epilepsy and lead to implantable technologies to stop or prevent seizures in patients. 

The researchers believe this is the first reported use of ultrathin, flexible silicon in a brain interface device. 

The research also holds promise for other medical applications, including dramatic improvements of existing implantable devices such as 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. 

Viventi is a member of the Electrical and Computer Engineering Department at NYU-Poly and the Center for Neural Science at NYU. The research was conducted with support from the U.S. National Institutes of Health’s National Institute of Neurological Disorders and Stroke and its National Heart, Lung, and Blood Institute; 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.

About Polytechnic Institute of New York University

Polytechnic Institute of New York University (formerly Polytechnic University), an affiliate of New York University, is a comprehensive school of engineering, applied sciences, technology and research, and is rooted in a 157-year tradition of invention, innovation and entrepreneurship: i2e. The institution, founded in 1854, is the nation’s second-oldest private engineering school. In addition to its main campus in New York City at MetroTech Center in downtown Brooklyn, it also offers programs at sites throughout the region and around the globe. Globally, NYU-Poly has programs in Israel, China and is an integral part of NYU's campus in Abu Dhabi. For more information, visit engineering.nyu.edu. 

About New York University

New York University, located in the heart of Greenwich Village, was established in 1831 and is one of America’s leading research universities. It is one of the largest private universities, it has one of the largest contingents of international students, and it sends more students to study abroad than any other college or university in the U.S. Through its 18 schools and colleges, NYU conducts research and provides education in the arts and sciences, law, medicine, business, dentistry, education, nursing, the cinematic and dramatic arts, music, public administration, social work, and continuing and professional studies, among other areas.