Better Electrodes for EEG Measurements

Measuring and visualizing brain waves is a key component of medical diagnostics: epilepsy diagnosis, research into sleep disorders, and tumor detection all rely on this technology. If attaching the electrodes were easier and the signal quality more consistent, electroencephalography (EEG) could be used for many more applications – from automated vision tests to early detection of dementia.

State of the Art

The current gold standard for EEG examinations relies on the use of adhesive and wet electrodes. For adhesive electrodes, the corresponding areas of the scalp usually need to be shaved. Alternatively, wet electrodes are used, which can be applied to a hairy scalp because they work with conductive gel. Due to gel residue, they require the hair to be washed. Sponge electrodes with saline solution represent another option, but they tend to dry out during longer measurements.

Technology

Researchers at the Institute for Information Processing Technologies (ITIV) at KIT have developed a flow-through electrode for measuring bodily functions that can be used even on unprepared skin surfaces and leaves virtually no residue. To achieve this, a closed electrolyte circuit with direct contact to the measurement site is used within an electrode housing. The 3D-printed housing contains internal channels through which the electrolyte is supplied, allowing electrical signals to be measured and transmitted to the sensing electrode. A channel structure ensures a dense spatial arrangement and thus high EEG resolution.

Application Example

Initial concrete applications relate to ophthalmology – such as measurements of the human visual field or automated visual acuity tests. In a closed-loop system consisting of a stimulus (e.g., a pattern display) and EEG measurement, the system uses brain activity to detect the moment when a test subject sees clearly. Since the stimulation patterns used here are also employed in many other examinations, they can be easily adapted to the new technology.

Options for Companies

KIT is currently developing suitable applications to analyze the signals for various purposes, including with AI support. Since this is a foundational technology, the invention could be widely used in medical and measurement technology. KIT is seeking partners for further development.