hydrogel-based brain sensors for enhanced adhesion

Innovative Brain Sensor Enhances Transcranial Focused Ultrasound for Neurological Disorders

Introduction to Transcranial Focused Ultrasound

This non-invasive technique, known as transcranial focused ultrasound, employs high-frequency sound waves to stimulate targeted brain regions, offering a potential breakthrough in treating neurological disorders like drug-resistant epilepsy and recurrent tremors.

Development of the Innovative Sensor

Researchers at Sungkyunkwan University (SKKU), IBS, and the Korea Institute of Science and Technology have designed an innovative sensor for transcranial focused ultrasound. Their study, featured in Nature Electronics, describes a flexible sensor that conforms to cortical surfaces, facilitating neural signal detection and low-intensity ultrasound-based brain stimulation.

Challenges with Previous Brain Sensors

"Previous efforts to develop brain sensors struggled to achieve precise signal measurement because they couldn't fully adapt to the brain's complex folds," remarked Donghee Son, the supervising author of the study, in an interview with Tech Xplore.

"The inability to precisely analyze the entire brain surface limited accurate diagnosis of brain lesions. Despite the innovative ultra-thin brain sensor developed by Professors John A. Rogers and Dae-Hyeong Kim, it encountered difficulties in tightly adhering to areas with severe curvature."

Limitations of Existing Sensors

The brain sensor created by Professors Rogers and Kim demonstrated improved precision in collecting surface-level measurements. However, it exhibited notable limitations, including difficulty adhering to areas with significant curvature and a tendency to shift from its attachment point due to micro-movements and cerebral spinal fluid flow.

The limitations observed reduce the sensor's suitability for clinical use, as they hinder its ability to capture brain signals reliably in specific areas over longer duration's.

The New Sensor Design

To overcome these challenges, Son and colleagues developed a new sensor designed for better adhesion to curved brain surfaces, ensuring stable, long-term data collection.

"The sensor we engineered is capable of conforming to even the most curved brain regions, ensuring a firm attachment to brain tissue," said Son. "This strong bond allows for long-term, precise measurement of brain signals from specific areas."

ECoG Sensor Features

The ECoG sensor designed by Son and his team attaches firmly to brain tissue, ensuring no voids are created. This feature markedly decreases noise from external mechanical movements.

"This feature plays a crucial role in improving the efficacy of epilepsy treatment using low-intensity focused ultrasound (LIFU)," noted Son. "Although ultrasound is recognized for its ability to reduce epileptic activity, the variability in patient conditions and individual differences present significant obstacles in customizing treatments."

Personalized Ultrasound Stimulation Therapies

Recently, numerous research teams have been focused on developing personalized ultrasound stimulation therapies for epilepsy and various neurological disorders. To tailor these treatments to the specific needs of each patient, it is essential to measure their brain waves in real-time while simultaneously stimulating targeted brain regions.

"Traditional sensors attached to the brain surface faced challenges in this regard, as the vibrations induced by ultrasound generated considerable noise, hindering real-time monitoring of brain waves," stated Son.

"This limitation significantly hindered the development of personalized treatment strategies. Our sensor substantially minimizes noise, facilitating effective epilepsy treatment through tailored ultrasound stimulation."

Structure of the Shape-Morphing Sensor

Son and his colleagues developed a shape-morphing brain sensor with three primary layers. These consist of a hydrogel-based layer for both physical and chemical bonding with tissue, a self-healing polymer layer that adjusts its form to fit the surface beneath, and a thin, stretchable layer containing gold electrodes and interconnects.

Son noted that when the sensor is positioned on the brain surface, the hydrogel layer activates a gelation process that establishes a strong and instant bond with the brain tissue.

"Subsequently, the self-healing polymer substrate starts to deform, adapting to the curvature of the brain, which enhances the contact area between the sensor and the tissue over time. Once the sensor has completely conformed to the brain's contours, it is primed for operation."

Advantages of the New Sensor

The sensor created by this research team offers multiple advantages compared to other brain sensors developed in recent years. Notably, it can securely attach to brain tissue while adapting its shape to conform tightly to surfaces, regardless of their curvature.

By conforming to the contours of curved surfaces, the sensor effectively reduces vibrations generated by external ultrasound stimulation. This capability enables physicians to accurately measure brain wave activity in patients, both in standard conditions and during ultrasound procedures.

Future Applications

According to Son, we foresee this technology being applicable not only for epilepsy management but also for the diagnosis and treatment of multiple brain disorders. The most crucial aspect of our research is the synergy between tissue-adhesive technology, which enables robust adhesion to brain tissue, and shape-morphing technology, allowing the sensor to conform precisely to the brain's surface without leaving any gaps.

Testing and Future Development

To date, the novel sensor engineered by Son and his team has undergone testing on conscious, living rodents. The results obtained were exceptionally promising, demonstrating the team's ability to accurately measure brain waves and mange seizures in these animals.

The researchers aim to expand the sensor's capabilities by developing a high-density array based on their initial design. Upon successful completion of clinical trials, this enhanced sensor could be utilized to diagnose and treat epilepsy and other neurological disorders, potentially adancing the effectiveness of prosthetic technologies.

With 16 electrode channels currently integrated into our brain sensor, Son highlighted an area ripe for improvement concerning high-resolution mapping of brain signals.

"Taking this into consideration, our strategy involves significantly augmenting the number of electrodes to enable comprehensive and high-resolution brain signal analysis. We also aspire to devise a minimally invasive implantation technique for the brain sensor on the surface of the brain, aiming for its application in clinical research."

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