American researchers have created dissolvable brain electrodes that can measure electrical activity in the brain with better resolution than existing devices
The implants, made of molybdenum and silicon, have been developed by a team from the University of Pennsylvania and described in the journal Nature Materials. The researchers were able to modify how long the device would stay in the brain of a rat by choosing the number of layers used and modifying the thickness of the device.
"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 Brian Litt, professor of neurology, neurosurgery, and bioengineering at the University of Pennsylvania and senior co-author of the study.
“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."
In the experiments, the researchers recorded brain waves in rats under anaesthesia, as well as voltage fluctuations between neurons (EEGs). They were also able to induce epileptic spikes in intact live tissue.
This type of measurement is usually performed to diagnose and treat disorders such as epilepsy, Parkinson’s disease, depression or chronic pain.
"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," Litt said.
In a separate experiment, the researchers tested a complex multiplexed array that could map rat-whisker sensing capabilities in high resolution.
The devices were placed on the surface of the brain cortex 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 data suggested that the dissolvable sensors performed as well or even better than currently used electrodes.
The team next plans to develop more complex devices that would be able to measure additional characteristics such as flow and pressure.