Neurological diseases like epilepsy, meningitis, or traumatic brain injury require the use of sensors that are in direct contact with the brain to guide surgery or monitor recovery in real time. Now, scientists have developed a brain probe that degrades once it is no longer needed, removing the need for surgical removal. 

“Many clinical situations require temporary monitoring of brain activity during the diagnosis and treatment of neurological diseases,” says Donghee Son, a professor at Yonsei University in Seoul, who led the development of the biodegradable sensor. “In these cases, electrocorticogram sensors are used. However, they require surgical removal through a second craniotomy, which poses the risk of infection, bleeding, and tissue damage.”

From the electrodes to the adhesive coating, all components of the sensor were especially chosen to be biodegradable under physiological conditions. After a few weeks, they gradually break up into a variety of non-toxic chemical compounds that can then be excreted naturally. 

In addition, the probe was designed to adapt to the intricate folds that give the surface of the brain its unique shape. This enables the sensor to stay attached and functional even as the brain moves with the person’s breathing, heartbeat, and body movement. 

To achieve this, the base of the sensor was made of a thin layer of polycarbonate-based polyurethane (PPU), a soft and flexible material with self-healing properties. The entire probe is also coated with an adhesive gel made of alginate, an organic material produced by algae that attaches well to soft tissues.

Inside the device, an ultra-thin layer of 12 electrodes is responsible for recording brain activity. The electrodes are made of molybdenum, a metal that is naturally biodegradable, safe to ingest, and resistant to corrosion. 

Patients with neurological conditions often undergo periodic magnetic resonance imaging (MRI) scans to monitor their progress, but conventional electrocorticogram sensors can distort these images. These sensors can also heat up or be displaced under magnetic fields, limiting their clinical applications. 

In contrast, the electrodes of the biodegradable sensor are designed to follow S-shaped patterns that not only enable them to remain functional as the sensor stretches over the surface of the brain, but also to minimize interference with MRI scans. 

Another important feature of the biodegradable probe is that the electrodes are only 2.5 mm away from each other—four times closer than in conventional electrocorticogram sensors. This can significantly increase the resolution and precision of the recordings and give researchers more detailed information about how the brain behaves, both in healthy individuals and patients with neurological conditions.   

Son and colleagues tested the device in rats, where the sensor reliably recorded brain activity for about three weeks. Afterward, the probe degraded into compounds that were then naturally excreted over time. 

By eliminating removal surgery altogether, the researchers hope this new sensor design will one day improve patient safety and shorten hospital stays. The technology could also help expand the applications of brain probes, which today are limited due to the risks associated with the surgeries required both to implant and remove these sensors. 

“In patients with neurological disorders such as epilepsy, the implanted sensor could capture seizure-related brain activity in real time to guide surgical strategies, whereas in patients with physical brain trauma, it could evaluate functional recovery during rehabilitation,” said Son. 

Before the technology can be tested in humans, more work will be needed to improve the sensor and ensure its safety. In future versions, Son and colleagues plan to increase the number of electrodes and give them the ability to transmit neural recording data wirelessly and in real time. 

Reference: Heewon Choi et al., Brain-Adhesive Bioelectronics With Shape-Morphable and Biodegradable Properties for Stable Brain Signal Monitoring, Advanced Science (2026). DOI: 10.1002/advs.202518255

Featured image credit: geralt via Pixabay