Executive Summary : | Electrocardiogram and electroencephalogram, or ECG and EEG, are two important health indicators that benefit from long-term monitoring. Dry and noncontact EEG electrodes have been identified as a significant enabler of real-world brain-computer interface (BCI) platforms, as they do not require gel or even direct scalp connection. This study compares wet electrodes to dry electrodes and noncontact electrodes through hair in a steady state visual evoked potential (SSVEP) BCI paradigm. A dry contact electrode with fingered contact posts and active buffering circuitry is demonstrated. It's also described how to make a novel noncontact capacitive electrode with a particularly integrated high-impedance analogue front-end. The signal quality from the various electrodes is characterised in offline investigations on ten participants, demonstrating that the unique integrated noncontact sensor can acquire data. The information transfer rate (ITR) achieved with dry electrodes is equal to that achieved with wet electrodes, without the use of gel or other conductive substances, according to online BCI experiments. Furthermore, data from the noncontact electrode, which works on the top of the hair, indicates a maximum ITR of more than 19 bits per minute with 100 percent accuracy (compared to 29.2 bits per minute for wet electrodes and 34.4 bits per minute for dry electrodes), a level never before demonstrated. These findings show that, with additional development, both dry and noncontact electrodes could become a viable tool for mobile BCI and general EEG applications in the future. The innovative electrode design bridges the gap between standard "wet" and "dry" electrodes, addressing the majority of their drawbacks while keeping the benefits of both. When a little amount of moisturising material (30 l) is released from a reservoir inside the electrode as a result of electrode/scalp adduction, a localised skin hydration effect occurs at the electrode/scalp contact site. The utility of the electrode is determined by the polymer's mechanical characteristics and the design of an electrode reservoir that deforms when a specified adduction force is applied. Numerical modelling methods were used to define and examine the electrode shape and material mechanical properties. The novel electrode prototype was able to monitor EEG signals that were equivalent to those of commercial silver/silver chloride electrodes while using only a fourth of the hydrating solution used by commercial electrodes, preventing hair damage and contamination. Owing to the little amount of moisturising agent utilised, the possibility of conducting bridges between nearby electrodes due to gel running is considerably reduced. |