# Usability and Acceptance Analysis of Wearable BCI Devices
## 5 Results
### State of the Art
This facilitates the application and disinfection of the system and keeps the user's head clean. In contrast to the NirSport (NIRx Medical Technologies, Berlin, Germany) device, which connects the cap to an external amplification system via a cable, the UHB device's built-in Bluetooth technology enables flexible electrode placement rather than a set configuration (like the Emotiv EPOCx, Emotiv Isight, Mindwave, Muse, Mindo, and Crown systems). Additionally, it enables direct access to streaming data through the Matlab and Python application programming interfaces, extending beyond coupling with the manufacturer's software. Another advantage of the system is its non-prohibitive price for application in field, clinical, or educational environments. In its basic configuration, the UHB uses the active hybrid electrodes of the g.SAHARA system--configurable with 8, up to 64 electrodes mounted on a conventional EEG headset--which allows data to be collected using electrodes connected to the amplification system with a magnet located in the central part of the neck. This makes the headset lighter, allowing a stable grip and freedom of movement on the part of the user. In addition, the system features adhesive ECG electrodes that are applied on the mastoids, which are useful for better characterizing the EEG signal, and an accelerometer and gyroscope system. A similar example is the Mindwave device, which has only one EEG electrode on the forehead, thus limiting its applicability. While UHB addresses significant drawbacks of existing systems, the restricted number of accessible channels may not be optimal for some applications [42]. Devices using conventional EEG headgear, such as the SAHARA, were substantially less favored than the others, according to overall design ratings [35]. For the most part, the Unicorn Hybrid Black devices are successful in being adaptable and delivering high-quality data outside of conventional laboratory settings [42]. The discomfort caused by pressure on specific scalp points, the overall weight or constriction of the unit, and discomfort during application and cleaning are the three main categories into which the system comfort issues reported by the participants in the reported studies can be divided [30]. On the other hand, necessities from a design and data collection point of view are the lack of interoperability, and thus the ability to dialogue with other systems and software not belonging to the parent company; signal quality due to numerous artifacts and a sometimes insufficient number of electrodes for a given application. Furthermore, factors and aspects related to emotional design are often overlooked: a discrete headphone design could have more potential to address different individual preferences, increasing visual pleasantness so as to entice the user to use the product [35]. For example, the visual appearance of the EPOCx device positively influenced users' comfort ratings. The advancement of sensor miniaturization techniques and the use of lightweight materials has led to significant improvements over the years in the design and perceptual aspect of wearable devices, especially in the field of neuroimaging devices, enabling them to be used even by non-specialized users. As shown in Figure 3, improvements in the design of the crowns focused on lightness, to the detriment of signal quality and the number of data recorded, focusing on aspects related to portability and formal acceptability. The Mindwave device (NeuroSky, San Jose, California, U.S.A.) year of production 2010, is, in fact, lightweight, allows dialogue with other technologies and software, but returns values recorded by a single sensor placed on the forehead. This implies its use for personal purposes only and not in industrial and/or medical and research contexts. Regarding conventional neuroimaging devices, the changes were substantial. Comparing NirSport (Nirx) and UHB, there is a clear improvement in perceived comfort levels.