Shielded Design of Screen-Printed EEG Electrode Set Reduces Interference Pick-Up

Thick-film technologies, such as screen printing, are becoming more popular in the manufacturing of bioelectrodes due to their simplicity, low cost, high reproducibility, and efficiency in large-scale production. Since electroencephalography (EEG) is a method for measuring potential differences in the microvolt scale, it is important to minimize all electromagnetic interferences. However, protecting screen-printed electrodes and their conduction traces from electromagnetic interferences has not been adequately investigated. We hypothesized that interference pick-up could be effectively reduced by an optimized silver or graphite shielded construction. The interference pick-up of the electrodes was technically evaluated in an electromagnetic compatibility laboratory and with EEG recordings of healthy volunteers. The grounding layer significantly (p< 0.001) reduced radio frequency (RF) interference in the standardized laboratory tests and the shielded electrodes exhibited significantly better power-line interference immunity in the EEG recordings (p< 0.05). The silver layer achieved better shielding in the RF tests than the graphite layer (p= 0.029). Since the silver layer is straightforward and cheap to produce with the screen printing technique, it could be advantageously used to shield, e.g., in emergency rooms where many interfering electronic devices are close to patient.