Sub-microwatt correlation integral processor for implantable closed-loop epileptic neuromodulator

Neuromodulation of the brain is an emerging therapy to control the epileptic seizure. The therapy can be improved with a closed-loop mechanism in which the electrical stimuli is activated in accordance with the seizure onset. In this paper, a correlation integral (CI) processor in a form of application specific integrated circuit is designed to estimate the brain complexity, chaoticity, after the EEG/ECoG sensors. Since the neural firing becomes more organized prior to the seizure, the intent is to drive the neuromodulator after the early detection of the seizure onset. With the simplified CI algorithm and channel-folded architecture, 0.14μW/channel power consumption is achieved in 90nm CMOS process to simultaneously extract chaoticity for 16 channels in a real time. The simulation results demonstrate a 98.23% and 97.81% of sensitivity and specificity for the classification of normal and epileptic brain rhythms.