Sequence of minimally invasive electrode insertion on a large brain surface using a biodegradable electronic tent. Credit: Jae-Young Bae, Seoul National University.
Sensors that can be easily and safely introduced into the brain could have important medical applications and contribute to the development of brain interface devices. Although significant progress has been made in the development of these sensors, most existing devices can only be deployed through invasive surgical procedures that can lead to numerous complications.
Researchers at Seoul National University and other institutes in South Korea have recently created a new biodegradable, self-deploying tent electrode that could be much easier to insert onto the surface of the human brain. Their proposed electrode design, described in Natural electronicscould degrade naturally inside the human body without leaving any residue, meaning that once inserted into the body, it does not need to be surgically removed.
“Our recent paper arose from a growing awareness of the clinical challenges of implanting electrodes via invasive brain surgery,” Seung-Kyun Kang, corresponding author of the paper, told Medical Xpress.
“Conventional large-area electrodes require extensive surgery to remove the skull before they can be implanted in the brain, which can carry significant risks of complications such as bleeding, swelling, cerebrospinal fluid leakage, or infection. After use, electrodes left on the brain can trigger adverse immune reactions or infections due to biofilm formation, requiring secondary surgery to remove them.”
The tent electrode created by the team is a pyramid-shaped sensing device, typically used to collect electroencephalography (EEG) recordings and other neurophysiological data.
“The electronic electrode we developed can be deployed using a syringe in a minimally invasive manner to measure brain signals, and can then be induced to dissolve and disappear into the body after use,” Kang said. “Our technology is particularly promising for precise diagnostics, such as epilepsy diagnosis, as well as neural prosthetics and brain-computer interfaces (BCIs) that require interfacing with various brain regions.”
The electrode developed by the team has a tent-like structure that can be easily packed and unfolded. The device is partly made from shape-memory polymers, flexible materials that can return to their original shape after being pulled or compressed in a narrow enclosure. Thanks to the properties of these materials, the electrodes can thus be easily introduced into confined spaces on the surface of the brain through a small hole.
The shape recovery and biodegradation process of the electronic tent. (a) Shape recovery process of the electronic tent in a skull and brain mimetic model. (b) Biodegradation process of the electronic tent in phosphate buffered solution (PBS; 70℃, pH 7.4). Credit: Adapted from Natural electronics (2024). DOI: 10.1038/s41928-024-01216-x
“We also integrated nanometer-thick biodegradable inorganic electronic sensors onto an electronic tent to provide flexibility,” Kang explained. “Due to the mechanical flexibility of the sensors, we were able to introduce various electronic devices without damaging the sensors during injection to measure various neurophysiological signals of the brain.”
Early tests evaluating the performance of the team’s tent electrodes have shown that they can maintain their electrical performance throughout their lifetime and completely decompose after use without leaving any residue. While in operation, the sensors can record electrical activity around them and transmit the data they collect to other devices.
Biodegradable and nontoxic, the new sensors developed by Kang and his colleagues would not need to be removed after being introduced into the human body. This feature is very attractive for a wide range of real-world applications, from precision medicine to the development of safe brain-computer interfaces (BCIs).
“The electronic tent can be used to diagnose epilepsy, which may require large-scale mapping to locate affected areas,” said Jae-Young Bae, lead author of the study. “Typically, epileptic seizures involve complex networks of brain regions, often located deep in the brain. Inserting electrodes into these deep and multiple regions to locate the origin of seizures can cause significant damage. In addition, because seizures are not constant, prolonged monitoring is often necessary.”
Existing methods for diagnosing epilepsy involve mapping brain activity over set periods of time, usually around two weeks. This is often done using electrodes that can capture what is happening in the brain, allowing doctors to pinpoint the origin of the seizures patients are experiencing.
Once doctors are able to diagnose epilepsy or identify other causes of seizures in a patient, they can begin to develop appropriate treatment interventions. But before they can do that, they must surgically remove the electrodes implanted in the patient’s brain.
The electronic tent is smoothly attached along the curved surface of the brain-mimicking fabric. Credit: Jae-Young Bae, Seoul National University.
“Our biodegradable electronic tent could reduce the surgical burden associated with implanting large-area mapping electrodes and eliminate the need for secondary removal surgery,” Bae explained. “The tent electrode can thus offer a minimally invasive diagnostic solution compared to traditional methods that require removing a large area of the skull for electrode insertion.”
In addition to aiding in the diagnosis of epilepsy and other brain diseases, the new tent electrodes could be used to develop functional neural interfaces (BCIs), emerging interfaces that could improve human-machine interactions and facilitate medical rehabilitation of patients.
“For example, BCI can help with the motor recovery of stroke patients and control neuroprosthetics or external robotic systems,” Bae said. “Large-area BCIs are more sensitive and can enable comprehensive mapping of brain regions, which allows for more precise localization of neural activity, facilitates the study of complex brain functions, and improves the targeting of therapeutic interventions. However, BCI technology faces challenges in terms of risks associated with invasive procedures. We believe that the tent-shaped electrode can minimize the risk of use in BCI technology.”
Kang and colleagues’ recent work may soon contribute to the development of safer ICBs and implantable devices for diagnosing various diseases. In their upcoming studies, the researchers also plan to explore the possibility of using various biodegradable materials to deliver targeted therapeutic interventions, such as chemotherapy and phototherapy.
“In the future, we also intend to collaborate with clinical partners to test our biodegradable e-tent technology in clinical applications,” Kang added. “This will allow us to conduct field trials in medical environments to evaluate the performance and degradation behavior of our technology outside of the laboratory. Ultimately, our goal is to integrate these biodegradable electronic components into medical devices, providing minimally invasive diagnostic or therapeutic solutions.”
More information:
Jae-Young Bae et al, A biodegradable and self-deployable electronic tent electrode for interfacing with the cerebral cortex, Natural electronics (2024). DOI: 10.1038/s41928-024-01216-x
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