Researchers at the University of Texas at Austin have developed electroencephalography (EEG) electrodes that patients can wear on their heads to monitor brain activity. The EEG electrode system acts as a brain-computer interface (BCI), which can be controlled by brain signals to help repair brain damage caused by stroke and other diseases.
The research results were published in the journal Biosensors and Bioelectronics. The results of the study show that the electrodes can be worn comfortably and stably for up to four weeks without any medical intervention. This is a huge improvement over existing electrodes, which typically need to be replaced every few hours or at most days.
Huiliang (Evan) Wang, assistant professor in the Department of Biomedical Engineering at the Cockrell School of Engineering and one of the project leaders, said: "We hope that people can wear this device for extended periods of time at home, where they can rehabilitate without having to continuously Going to the clinic or rehab every day for weeks, when you're recovering from a stroke, it's even more challenging."
There are two main types of current EEG electrodes, dry and wet, but neither of these electrodes works well for long-term continuous monitoring. Gel-based wet electrodes do a better job at recording brain activity, but require more maintenance than dry electrodes.
This new electrode takes the advantages of wet gel electrodes and eliminates major drawbacks such as their tendency to dry out and then fall off.
Electrodes are applied to humans. Source: University of Texas at Austin
The researchers took this idea a step further by combining conductive polymers with polymers with high water content. This allowed them to take advantage of the benefits of the gel-based material, mainly due to interference caused by skin and hair, a concept known as electrode-skin impedance.
The electrode system records brain activity, such as the brain telling a hand to move. However, a stroke can disrupt nerve pathways between parts of the body, making it more difficult to signal action. The combination of a brain-computer interface and functional electrical stimulation can turn the idea of moving a body part into an action that stimulates the target area to execute brain commands. This approach can help rebuild the communication pathways between the brain and other parts of the body damaged by a stroke.
Demonstration of combining POLiTAG electrodes with a wireless single-channel EEG device
"These new EEG electrodes have the potential to revolutionize the field of non-invasive EEG interfaces, which currently require extensive expert support every time the system is set up," said researcher Del Millán. "Furthermore, since mastering BCI and inducing functional recovery and Brain plasticity requires subject training, and having a permanent system that people can use autonomously throughout the day will enhance the potential of this technology."
The next step for the researchers is to expand how long the electrodes can be worn, and the types of activities this wearable EEG-based brain-computer interface can facilitate. They are also working on applications such as controlling wheelchairs and moving prosthetics.