A Micro-power EEG acquisition SoC with integrated seizure detection processor for continuous patient monitoring

Continuous on-scalp EEG monitoring provides a non-invasive means to detect the onset of seizures in epilepsy patients, but cables from the scalp pose a severe strangulation hazard during convulsions. Since the power of transmitting the EEG wirelessly is prohibitive, a complete SoC is presented, performing lowpower EEG acquisition, digitization, and local digital-processing to extract detection features, reducing the transmission-rate by 43x. To maximize power-efficiency, the acquisition LNA operates at the lowest reported VDD (of 1V, drawing 3.5µW), but is able to reject offsets (characteristic of metal-electrodes) that are even larger than the supply voltage. Importantly, its topology simultaneously optimizes noise-efficiency and input-impedance to maximize electrode signal-integrity, and it uses switch-capacitor transformers to improve the noise and manufactureabilty of large on-chip resistors. The complete SoC generates EEG featurevectors every 2sec, consuming a total of 9µJ per feature-vector.