Kapazitives EEG-Helmsystem für BCI-Anwendungen

Brain-Computer Interfaces (BCI) are novel additional communication systems between human and machine, which means between human and his environment. They work without using the peripheral nervous system, thus without moving extremities or using language. Instead, they allow sending commands from brain to computer directly. For patients with locked in syndrome or paraplegia, this is in many cases the only way to communicate with their environment. Further applications could be for machine control or computer games. Due to high time resolution and direct reflection of neural processes, in this work non-invasive capacitive electroencephalography (cEEG) is used for signal acquisition directly at the head surface. The electrodes are integrated in a helmet, made by rapidprototyping. The applied development of the wireless 25-channel cEEG helmet is therefore one key aspect of this work. After data transfer to a PC, the developed software translates them into control commands. Their execution gives a biofeedback to the user, with it he can keep the control over the complete system. In this work, the realization of an application for writing (speller) by steady-state visually evoked potentials (SSVEP) is in focus. The measured signals are visually evoked by a flickering checkerboard pattern. For optimal functionality, adjustment of stimulation and software based data analysis to the particular user is necessary. This was proven by color-frequency scans (CFS). Here, individual reactions of the brain to signals with different colors and frequencies are evaluated and best combinations for application control are identified. Due to consideration of different interfaces and subprocesses of the complete system, a multidisciplinary work emerged. It covers electrotechnical and design-based as well as mechanical and medical challenges. Thus, BCI is with its multitude of application areas a promising topic, however the ethical questions have to be focused as well. They arise essentially with the identification and realization of human will without visual impulse exclusively by brain signals.