An adhesive cortical device enables artifact-free neuromodulation for the treatment of closed-loop epilepsy

A team of researchers has developed a soft cortical device that could revolutionize the treatment of epilepsy and other neurological disorders.

The group is led by Professor Son Donghee and Professor Shin Mikyung from the Center for Neuroscience Imaging Research (CNIR) within the Institute for Basic Science (IBS), together with Dr. Kim Hyungmin of the Bionics Research Center of the Korea Institute of Science and Technology (KIST).

Epilepsy, a neurological disorder that affects more than 65 million people worldwide, is characterized by pathological electrical hyperactivity in the brain, resulting in seizures. Strikingly, approximately 20% to 30% of all patients are diagnosed with intractable epilepsy, which does not respond to standard medications.

Surgical resection of lesions remains a treatment option for these patients, but presents challenges due to the complexity and risks associated with the procedure.

As a less invasive alternative treatment, the concept of neuromodulation has been proposed, in which damaged tissue is directly stimulated with mechanical, electromagnetic or optical energy to suppress brain hyperexcitability.

One promising approach is transcranial focused ultrasound (tFUS) neurostimulation, a non-invasive method that stimulates the brain with high precision without causing permanent damage.

For tFUS to be effective in treating epilepsy, it must be linked to a system that can continuously monitor brain activity and adjust treatment in real time. However, existing cortex interface devices face challenges due to their high stiffness and low shape adaptability, which makes it difficult for them to adapt to the complicated surface of the brain, resulting in poor tissue-device interfaces.

Their low adhesion to the brain surface also means that they struggle to deliver accurate brain signals during ultrasound stimulation, due to the interference caused by the mechanical pressure waves.

To address this challenge, the research team developed the Shape-Morphing Cortical-Adhesive (SMCA) sensor, a soft, flexible device that adheres closely to the brain surface and ensures stable and accurate monitoring of brain activity even during tFUS stimulation. The findings are published in the news Natural electronics.

The SMCA sensor is composed of a unique combination of materials. It features a layer of catechol-conjugated alginate hydrogel that quickly adheres to brain tissue, creating a strong bond and reducing the risk of movement or detachment.

Additionally, the device’s substrate is made of a self-healing polymer that softens at body temperature and conforms to the curved surface of the brain, ensuring a snug fit and minimizing the risk of signal artifacts.

The team tested the SMCA sensor both ex vivo (outside the body) and in vivo (inside the body), comparing its performance to that of existing devices without adhesive or shape-shifting features. In experiments using a rat epilepsy model, the SMCA sensor successfully recorded brain activity during tFUS without interference, enabling the real-time monitoring necessary for effective treatment.

Using this innovative sensor, the researchers implemented a closed-loop seizure control system. This system uses the SMCA sensor to detect early signs of an attack and automatically adjusts the tFUS treatment. The system successfully suppressed seizures in real time, demonstrating the potential for personalized, adaptive epilepsy treatment.

Professor Donghee said: “Through our research on the brain adhesive soft bioelectronics platform, we have overcome a major challenge in brain interfaces by achieving high-quality electrocorticography combined with focused ultrasound stimulation without artifact interference.

“We expect our technology to become a cornerstone of a next-generation biomedical platform that enables accurate diagnosis and personalized therapy for intractable neurological diseases.

“Following this study, we will further develop the SMCA sensor platform by improving its shape-shaping and cortex-adhesive functionalities, developing highly integrated microelectrodes, and implementing a high-order closed-loop operational algorithm.”

Dr. Kim said: “We achieved early detection of seizure activity via ECoG, which helped prevent seizures. In addition, we implemented real-time feedback on the effects of ultrasound stimulation, allowing the application of personalized stimulation protocols.

“Looking ahead, we expect that the development of multichannel electrodes, as well as multichannel ultrasound transducers, will facilitate accurate mapping of seizure sources and targeted interventions, ultimately increasing the efficacy and safety of this approach in clinical applications.”