Record an eye blinking waveform signal from EEG signals I want to Record an eye blinking waveform signal from EEG signals , but it need to make a quiscent periods of recording , So how to make this quiescent periods(i.e the signal has a zero amplitude at all time in the quiescent recording except the eye blinking time)?
You can't. 


Flatline EEG is how brain death is defined, and while it may be possible to induce an eye blink in a deceased human, I am sure ethics will not approve, and it won't be scientifically satisfactory. 
even in the case of a real flatline EEG, there will always be some remaining residual activity (albeit very weak), such as line noise. 


However, 


the eye blink is a few orders of magnitude stronger than the ongoing EEG
you can isolate eye blink activity using techniques such as ICA