New portable and non-invasive device to know brain activity

Electroencephalography is a technique that collects brain signals and records the electrical activity of the brain. The way to obtain these signals is through an electrode cap that covers the head and allows the electrodes to be attached to the scalp. The limitations of these devices are their size and weight since, due to their own characteristics, they are uncomfortable for users and difficult to transport.

To solve these problems, two researchers from the Polytechnic University of Madrid (UPM) in Spain are working to develop an electroencephalography device that, placed on the head, is as small, comfortable and portable as possible and that can be used 24 hours a day, 7 days a week. days a week, anywhere. It could be used in neurological diseases such as stroke, Parkinson’s, Alzheimer’s or depression, so it could improve both diagnosis and treatment. It would allow early and focused diagnoses, and more personalized treatments without the need for hospitalization.

The work being carried out by Ana Carretero and Álvaro Araujo, both members of the research group: B105 Electronic Systems Lab, focuses on brain-computer interfaces to obtain information about the motor area of ​​the brain, trying to search for the intentionality of movement . Upon detection, the device knows the movement the person wants to execute and this information can then be delivered to the specific muscles and nerves needed to initiate the intended movement as intended in the brain.

The objective of their work is to provide clarity to decisions on the number of electrodes required for wearable EEG, taking into account the algorithms developed and their complexities to address calculation problems. “Our goal is to design an optimal motor image acquisition device that strikes a balance between the information obtained and usability,” the researchers say.

To do this, Ana Carretero and Álvaro Araujo are carrying out experiments using various combinations of electrodes placed in areas related to movement in the brain (mainly, the motor cortex and the supplementary motor area, as well as other secondary areas). Public patient data is used in the trials, in addition to that generated in its laboratory. This allows us to study some more technical characteristics for the design of the device, such as the number of electrodes, the degree of training and the amount of data needed.

The results show that it is possible to detect thought or imagined hand movement with a probability between 94% and 95% using only a non-invasive electrode in the motor cortex. Furthermore, after carrying out prior training, it would be possible to detect the movements of each finger on the hand with a reliability of between 92 and 94 percent.

Present: electroencephalography machine with electrode helmet in hospitals. Future: Non-invasive portable wearable device placed on the head. (Image: Ana Carretero Pérez)

After completing the experiments, the next step in the project will be to develop a device that adapts to these design decisions in order to study the maximum performance that a very small device can allow.

“The overall conclusion is that a portable, low-electrode EEG device is feasible with algorithms that generate outputs at real runtime. Consequently, we can develop a portable and comfortable device for patients with specific requirements,” concludes Ana Carretero.

This work is part of the MINA-CM project funded by the Community of Madrid and is aimed at the rehabilitation of patients who have suffered a stroke. The use of this technology together with transcranial magnetic stimulation technology would allow them to improve their rehabilitation in terms of time and mobility.

The study is titled “Design Decisions for Wearable EEG to Detect Motor Imagery Movements.” And it has been published in the academic journal Sensors. (Source: UPM)