Biosensors
Electrophysiological signals, measured from skin electrodes, allowed us to evaluate brain-, heart- and muscle-activity, eye movements, respiration, galvanic skin response and many other physiological and physical parameters. The core of our electrophysiological recording devices consisted of a 32-channel multi-purpose USBamp system (gTec, Austria) as well as a wireless 64-channel EEG system (Brain Products, Germany). In addition, we employed stand-alone sensors for dedicated experimental setups.
The 32-channel multi-purpose USBamp system consisted of two modular 16-channel amplifiers that were primarily used for EEG recording. Nonetheless, it was also compatible with a range of sensors for measuring blood-pulse, skin-conductance activity and respiration. Thus, this system was useful for measuring EEG and peripheral biosignals simultaneously.
The wireless 64-channel active electrode EEG system was ideal for laboratory spaces that required user mobility, such as motion simulators. It consisted of modular DC amplifiers and additional amplifiers could be introduced to extend this system to 128 channels. LEDs on the electrodes indicated the local impedance, thus facilitating EEG preparation and ensuring consistent accuracy across the electrodes. The same system had a LED-based digitizer that allowed for quick localization mapping of the EEG electrodes. This allowed for more accurate EEG source localization analyses.
In addition, a portable and multi-purpose 16-channel V-amp amplifier (Brain Products, Germany) was used to manage the mobile recording of electrophysiological signals (e.g., EMG, ECG, EEG) as well as biosignals such as respiration rate. This system could be extended with different sensors for multiple physiological measures including respiration, temperature, skin conductivity and blood pulse. For example, we employed a piezo-electric crystal sensor in a robust belt system that could be used to record chest or abdominal respiration waveforms. Such a system could be used to record breathing frequency and to provide bio-feedback in a virtual reality application.
The Q Sensor is a stand-alone wireless device that allowed the wearer to conveniently record skin conductance as function of sympathetic nervous system activity. It could sample up to 32Hz and was used as a tool for psychophysiology experiments.
In order to assess postural stability which can correlate with motion sickness levels a Nintendo Wii Balance Board was used. Research has shown that the Balance Board is a viable alternative to force plate measurements. Internally it consisted of 4 force sensors and samples center of pressure data at 60 Hz.