Wearable Bioimpedance Hydration Monitoring System using Conformable AgNW Electrodes

Monitoring hydration level could be vital for maintaining physiological and cognitive performance during physical exertion and thermal stress. We present a custom miniaturized wearable bioimpedance spectroscopy (BIS) system consisting of a Bluetooth-enabled system-on-a-chip and an analog front-end circuit integrated with conformable, flexible, and stretchable silver-nanowire electrodes. This system is capable of performing four-electrode BIS at a range of frequencies between 5 kHz and 195 kHz, transmitting the data wirelessly to a data aggregator, and configuring the front-end circuit parameters over-the-air when needed. A 150 mAh lithium polymer battery can power the system for 18 hours. In this study, proof-of-concept in-vitro validation of the system generated promising results.