# Electroencephalography (EEG) Technology Applications and Available Devices
## 5 Discussion  
To select an EEG device, it is necessary to look at a variety of factors, some of which are listed below:  
* **Designing Technology Dry/Wet (saline or gel):** Unfortunately, there are few studies done on this area. Recently, some researchers [35; 37] compared a dry and wet headset for their research and they concluded that although the selected dry EEG headset was more robust to line noise, it contained more artifacts;
* **Setup time:** Regardless of the connection type being used, the setup time for EEG electrodes tends to be longer than for most physiological sensors. Saline-based sensors are usually selected for their ease of use and quick setup time, relative to gel-based sensors. Gel based EEG devices demand a larger amount of time, relative to other connection methods, to apply, while the saline headset does not take much time to set up. Cleaning saline headsets after using them takes less time than gel-based sensors. The gel also sticks to the hair of participants, which could be uncomfortable and inconvenient for users;
* **Signal quality and stability:** Quality of the captured EEG data depends on several factors: connection stability, losing connection with the scalp, and wireless, which are described below: 1. **Losing Connection with the Scalp:** The quality of the recorded EEG data highly depends on the connection between electrodes and the scalp. Gel-based sensors are usually chosen for their stability of connection and longevity, as the wet or gel-based sensors maintain a more stable connection for several hours, while wet and dry EEG headsets may lose humidity during an experiment, which can lead to a decline in signal quality. To have stable, high-quality and reliable EEG data, it is necessary to make sure that all relevant electrodes are connected and do not lose their connection during experiments by reapplying the saline solution to the electrodes, as the solution evaporates over time. In order to maintain a stable connection over long periods, it is necessary to reapply the saline solution to the electrodes, as the solution evaporates over time;
2. **Wireless Connectivity:** Wireless EEG devices can pose a security risk to the data of the participant, as any movement of cables could potentially induce the data during transfer. Because of this, wireless EEG devices should necessarily require encryption of the data prior to wireless transfer. * **Headset Size:** Most EEG devices are limited in their size adjustability, and may thus require multiple different caps or headsets in order to fit experiments and studies which collect data of individuals with large head-size discrepancies, increasing the overall price;
* **Battery Life:** Wireless EEG devices are most often battery-operated and, as such, are subject to potential loss of data if the current battery charge falls below threshold levels. Ensuring that batteries will be operational throughout long studies can be difficult, and the necessity of ensuring batteries are charged increases the complexity of data-gathering using EEG devices. Battery life has a negative correlation with the amount of sensory information they provide; as more information is given, the battery time decreases, which means that the research focused on long-term study of brain activities should try to rely on less sensory information, if possible;
* **Sensitivity to external noise/artifacts:** When collecting EEG data, it is important to ask the participants to sit in a relaxed manner because any movement of the body can cause artifacts in the data.