Planting Electronics in the Brain

Bisection of the head of an adult female, showing the cerebral cortex, with its extensive folding, and the underlying white matter. image from wikipedia

 An implantable brain device that literally melts away at a pre-determined rate minimizes injury to tissue normally associated with standard electrode implantation, according to research led by a team from the Perelman School of Medicine at the University of Pennsylvania. …Thin, flexible neural electrode arrays with fully bioresorbable construction based on patterned silicon nanomembranes (Si NMs) as the conducting component.

“Dissolvable silicon electronics offer an unprecedented opportunity to implant advanced monitoring systems that eliminate the risks, cost, and discomfort associated with surgery to extract current devices used for post-operative monitoring,” said senior co-author Brian Litt, MD,….“This study tested the usefulness of temporary, dissolvable monitoring systems capable of providing continuous streams of data for guiding medical care over predetermined periods of time — from days to months — before dissolving.”

The device is made of layers of silicon and molybdenum that can measure physiological characteristics and dissolve at a known rate, as determined by its thickness. For example, the team used the device to record brain waves in rats under anesthesia, as well as voltage fluctuations between neurons (EEGs), and induced epileptic spikes in intact live tissue. A separate experiment demonstrated a complex, multiplexed array made from these materials that could map rat-whisker sensing capabilities at high resolution.

These electrophysiological signals were recorded from devices placed at the surface of the brain cortex (the outer layer of tissue) and the inner space between the scalp and skull. Chronic measurements were made over a 30-day period, while acute experiments demonstrated device operations over three to four hours.

The type of neurophysiologic features measured by the new device are commonly used for diagnosing and treating such disorders as epilepsy, Parkinson’s disease, depression, chronic pain, and conditions of the peripheral nervous system. “….

This work was funded by the Defense Advanced Research Projects Agency, the Penn Medicine Neuroscience Center,  and others.

See Next-Gen Electrodes: Proof-of-Concept Animal Study Shows that Flexible, Dissolvable Silicon Electronic Device Holds Promise for Brain Monitoring , Press Release, May 5, 2016

See also Nature Materials

The US Military and the Peripheral Nervous System

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