An eye blink artifact is formed with a gradual increase and decrease generally within 100 and 500 ms [11], [31], [32] and [33], whereas the EEG signals cover wider frequency ranges (0.5–50 Hz and above) [34] and [35] (see the first figure in Fig. 1 for a schematic representation of a contaminated EEG signal). When a sliding window is set to be large enough to cover multiple ripples of an EEG waveform, as shown in Fig. 1, the summation of the first-order derivatives of the raw signal within the sliding window will filter out the ripples. When the sliding window size is set to be approximately half the width of the target eye blink wave and the window slides along the time axis, the filter output (the summation of the first-order derivatives within a sliding window) can distinctly extract the presence of the target wave while suppressing other ripples with smaller periods than the target wave, as depicted in Fig. 1.