Dissolvable silicon electronics offer an unprecedented opportunity to implant advanced monitoring systems, according to researchers from the Perelman School of Medicine at the University of Pennsylvania. Implantable brain devices that literally melt away at a pre-determined rate, for example, may minimize injury to tissue normally associated with standard electrode implantation.

The University of Pennsylvania 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.

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

The 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.

“These measurements are critically important for mapping and monitoring brain function during and in preparation for neurosurgery, for assisting in device placement, such as for Parkinson's disease, and for guiding surgical procedures on complex, interconnected nerve structures,” said Brian Litt, MD, a professor of Neurology, Neurosurgery, and Bioengineering.

The devices could also be used by heart and brain surgeons for such applications as aneurysm coiling, stent placement, embolization, and endoscopic operations. The new technologies could monitor structures that are exposed during surgery but are too delicate to disturb after initial operations to remove devices.