Low power bioimpedance tracking system for stress and activity monitoring

Abstract

Simple low power circuit for bioimpedance tracking on different frequencies is purposed in this paper. Using ADC and digital signal processing is intentionally avoided to reduce power consuming and processing power required. Instead only analog comparators and digital timers are used to determine signal phase, amplitude and calculate impedance with noise correction. Programmable system on chip (PSoC) is used for prototyping to emulate circuit work and run performance tests. Measurements performed on two volunteers display bioimpedance changes as a reaction on person's physical activity, alcohol intoxication and wake up from sleep. Circuit is simple to implement in silicon and is suitable for wearable devices where space and energy economy is critical.