Acticap xpress

Brain Products actiCAP Xpress is a 16-channel dry EEG system (actiCAP system, Brain Products Xpress, Germany). The electrodes are worn in a flexible rubber cap and can easily be removed and replaced by fitting the electrodes within holes in the cap corresponding to the extended 10–20 international electrode nomenclature system. The dry sensors, known as Quick Bits, are flat T-shaped and round mushroom shaped electrodes for direct skin and scalp contact. The round shape of the mushroom-headed sensors allows for contact with the scalp without requiring the electrodes to be perpendicular to the head, while the T-shaped sensors allow direct skin contact with a high surface area for hairless and frontopolar positions. For these experiments, EEG data were online referenced on the subject's earlobe and the data were collected at a sampling rate of 512-Hz. The open-source 2015 version of the software OpenViBE (Renard et al., 2010 (link)) was used for development of an experiment-specific application. The EEG cap was wire-connected to a Microsoft Surface Pro (Microsoft Corporation, Richmond, WA) and the data were stored directly on the device during the experiment.

The volunteers were instrumented with one of four dry electrode EEG caps: Mindo-32 Trilobite (M32; National Chiao Tung University Brain Research Center¹), Mindo-4S JellyFish (M4S; National Chiao Tung University Brain Research Center²), Neuroelectrics Starstim (SS; Neuroelectrics³), and Brain Products actiCAP Xpress (BPD; Brain Products GmbH)⁴. In addition, separate volunteers were recruited to participate in the experiment while wearing a traditional gel-based EEG cap: ActiCAP active electrodes with BrainAmp DC amplifier (BPG; Brain Products GmbH⁵). The dry electrode systems were loaned by the companies that manufactured them: two devices for M4S, four devices for M32, one device for SS, two devices for BPD, and one BPG system. The devices arrived at the experiment location at different times. Their cumulative usage is shown in Figure 1. Table 1 outlines the technical specifications of each of the systems.

Electroencephalogram (EEG) and Electromyography (EMG). were recorded simultaneously at 512 Hz sampling rate using a dry-active electrode cap (BrainVision, actiCAP Xpress, BrainProducts-Germany) with 11 scalp channels following the standard 10–20 International System, two channels for EMG, one channel for EOG (Electrooculogram), and one for additional reference. The ASR was recorded through EMG using electrodes placed 2 cm below the pupil (EMG1) and 2 cm below right eyes outer end (EMG2). Primary reference was attached to the right earlobe with the additional reference electrode placed on the left earlobe.