An EEG monitoring device, contains at least one electrode, a non-linear analog signal processor, a variable resolution analog-to-digital converter, a storage, and a power source. The non-linear analog signal processor receives a signal from the at least one electrode and determines whether the signal is within a significant category. The variable resolution analog-to-digital converter converts signals received from the non-linear analog signal processor into high-resolution digital signals if the signals are within the significant category, and converts signals received from the non-linear analog signal processor at a low resolution if the signals are not within the significant category. The storage stores high-resolution digital signals received from the variable resolution analog-to-digital converter and the power source is connected to, and provides power to, the non-linear analog signal processor, the variable resolution analog-to-digital converter, and the storage.
