Classic electrode solutions
Traditionally, bridge electrodes, cup electrodes or electrode systems with pre-installed electrodes according to the international “10-20%” system are used to record the electroencephalogram. Less commonly used are disposable hydrogel electrodes (usually in neonatology) and subdermal needle electrodes (usually in intensive care units). Invasive EEG electrodes are a separate class.
Future-proof electrode solutions
In addition to traditional ones, innovative EEG electrodes are currently appearing in the form of dry active electrodes.
Unfortunately, the use of dry electrodes is still associated with certain difficulties. With all their advantages (speed of application, dry and clean hair after examination), they also have a number of significant disadvantages. First of all, such electrodes are quite expensive. It must be said that recently they have been trying to solve this problem by replacing dry electrodes made of precious metals with various polymer materials. But still, the quality of EEG recording using such electrodes remains rather mediocre. Such electrodes cannot be applied with the required impedance level, which significantly increases the noise level and reduces the recording quality.
A new wave in EEG recording without gels and pastes
In 2023, thanks to the development of innovative materials, electrode systems were proposed that combined ease of use, speed of application and subsequent drying and disinfection. Such electrode systems are based on traditional silicone helmets with pre-installed cup electrodes according to the “10-20%” system, but instead of gel, sponges made of innovative absorbent material are used to ensure electrical contact with the scalp. Before using such systems, they should be soaked in a saline solution so that the sponges are saturated with saline. Before placing the cap on the patient's head, shake off excess moisture. Electrical contact is ensured by impregnated sponges under each cup electrode. After use, the system is easy to clean and disinfect. This saves a significant amount of time when conducting routine EEG examinations.
An example of such an electrode system from the Chinese manufacturer, Teveik. The number of channels can vary from 21 to 256.
Below is a simple algorithm for using such EEG systems, consisting of simple six steps.
- Preparatory step: checking the equipment set, which includes: a silicone helmet, cup electrodes, connection cable, sponges and a container for soaking the cap in saline solution.
- First step: connecting the system to EEG recording equipment. The connection can be made by using touchproof connectors or using one common connector for the electrode cap. Teveik electrode systems are fully compatible with Neurosoft EEG equipment and can be connected in any of the proposed ways. Teveik electrode systems for Neurosoft equipment are supplied assembled with a common connection cable.
- Second step: soak the electrode system in a 5% saline solution.
Note: The system must be soaked for at least 20-25 minutes before first use.
- Third step: installation of the electrode system on the subject’s head. It is necessary to shake off excess moisture and place the helmet on the patient’s head in accordance with the requirements of the “10-20%” system.
- Fourth step: impedance measurement. After the system is applied, it is necessary to measure the level of subelectrode resistance (impedance).
- Fifth step: adjusting the position of the electrodes. If the impedance level is unsatisfactory, it is necessary to move the hair on the patient’s head at the points of contact of the soaked sponges with the scalp until the impedance level decreases to an acceptable level. For convenient work with hair, the system includes a special plastic spatula. To ensure a tight fit of the electrodes, it is necessary to adjust the chinrest using tightening straps.
- Sixth step: cleaning, disinfection, drying. After completing the recording of the examination, the electrode system should be removed from the patient’s head, rinsed with running water and disinfected. After disinfection, the system should be rinsed again with running water. The system is ready for use again. If no more examinations are planned on that day, the system should be placed in a dryer.
Description of the recommended electrode system disinfection option:
Conclusion:
Thus, the use of new electrode systems makes it possible to simplify and significantly speed up short routine EEG examinations.
Teveik company contacts:
Useful materials
- 10-20% System: Electrodes Placement.