Wearable eeg/eit system for monitoring and enhancing glymphatic clearance (gc) during sleep using skin-path-corrected single-frequency impedance to compute a gc index with gc-window-gated stimulation

Abstract

A system for electrical stimulation and recovery of impressed currents during sleep to measure the electrical impedance of intracranial tissue through a single-frequency current stimulation, and decrease the brain impedance through other stimulation parameters, thereby increasing extracellular space and improving glymphatic flow (as indexed dynamically by the concurrent brain impedance measure). A skin-path-correction factor is estimated to allow the subtraction of the electrode-to-skin impedance and thereby estimate the brain impedance compartment separately. Based on computational modeling of electrical conductivity of head tissues, the electrodes are placed at forehead and nuchal sites to optimize current flow through high-conductive skull orifices. Current flow estimation is monitored at the critical orifice of the foramen magnum, and safety limits are monitored and enforced for individual electrodes and for key brain structures.