Current market solutions available include conventional gel electrodes, which are widely used for biopotential measurements such as ECG and EEG monitoring. They are administered during treatment or diagnosis by medical specialists in hospitals, and incur the drawbacks of skin irritation, arduous application and uncomfortable removal. Dry electrodes have also been introduced, and enable wireless biopotential monitoring systems for use outside the domain of the medical specialists during daily activities. However, first generation solutions consist of rigid metal pins that lend to discomfort and pain in patients.
Fabricated from ethylene propylene diene monomer (EPDM) rubber, containing various additives for optimum conductivity, flexibility and ease of fabrication, the polymer dry electrodes offer a high user comfort. Polymer composition is optimised for noise from phantoms and human skin on skin-electrode impedance, resulting in a skin-electrode impedance approximately 10 times greater than that of gel electrodes. The electrodes are directly capable of recording strong biopotential signals such as ECG, and low-amplitude signals such as EEG.
In relation to EEG signals, the polymer electrodes are coupled with an active circuit, forming a so-called 'active electrode.' EEG recordings on imec’s prototype wireless EEG headset – the nanoelectronics research centre, and the associated Holst Centre, have a prototype wireless EEG headset and health patch, demonstrating their innovative technology solutions for remote monitoring – using these active polymer electrodes proved very promising results, showing similar performance compared to the performance using metal dry electrodes on imec’s wireless EEG headset. At the same time the comfort of the user is substantially improved when using polymer electrodes.