Tiny Folding Implants to Reduce Surgery for Treatment of Brain Conditions

Around 50 million individuals globally suffer from epilepsy, a condition linked with up to three times higher risk of premature death compared to the general population. Accurate diagnosis and treatment of epilepsy require monitoring brain electrical activity, traditionally necessitating a craniotomy—where a large section of the skull is removed to place electrodes directly on the brain. This method is highly invasive, has a lengthy recovery period, and carries a high risk of infection. Researchers have now developed innovative 'origami-inspired' brain electrodes that become significantly smaller after they fold to a fraction of their full size. This development could drastically reduce the surgical burden for treating neurological conditions like epilepsy or for implementing brain-computer interfaces.

In a new study published in Nature Communications, a research team led by the University of Oxford (Oxford, UK) and the University of Cambridge (Cambridge, UK) has detailed these new folding brain electrodes designed to minimize the incision required—reducing it by approximately five times without compromising their functionality. In its expanded state, the electrode system looks like a flat, rectangular silicone wafer about 70 microns thick (roughly the width of a human hair) with 32 electrodes connected to a cable. This wafer folds accordion-style to fit through a mere 6 mm slit. Positioned on the brain's surface, a pressurized fluid-filled chamber within the wafer inflates, unfolding the device to cover an area of up to 600 mm². Normally, implanting a non-folding device of similar dimensions would require removing at least 600 mm² of the skull.

Image: The thin-film soft robotic electrode array is designed for safer and less invasive epilepsy surgical mapping (Photo courtesy of University of Oxford)

The device's effectiveness was validated through tests on anesthetized pigs, confirming that the unfolded electrodes could accurately capture and record brain activity. The research team suggests that this fold-up electrode could be used in human patients within a few years. They also believe that the innovative fold-up design could reduce the extent of surgery required for installing brain-computer interfaces, benefiting individuals with disabilities and enhancing human-computer interactions.

“This study presents a new approach to directly interfacing with large areas of the brain through a key-hole like surgery,” said Christopher Proctor, Senior Author and Associate Professor at the Department of Engineering Science, University of Oxford. “The potential significance of this work is two-fold. First, there is the promise of a less invasive diagnostic tool for epilepsy patients. Second, we envision the minimally invasive nature will enable new applications in brain machine interfaces.”

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University of Oxford
University of Cambridge