A Wearable Device to Measure Bioimpedance and Electrodermal Activity.

Continuous non-invasive health monitoring requires wearable devices capable of capturing synchronized, multi-parametric physiological data without compromising user comfort or signal integrity. However, existing platforms often suffer from insufficient accuracy in complex modalities such bioimpedance. To address these limitations, this paper introduces the Multi-sensor Wearable Wristband Version 2.0 (MsW2-v2), an optimized, highly integrated platform designed for high-precision measurements. The methodology encompasses the hardware optimization of a previous prototype, integrating a low-leakage switching matrix and dual-bandwidth analog front ends to capture, in a quasi-simultaneous (time-multiplexed) manner, electrodermal activity (EDA) and bioimpedance (BiZ), as well as other physiological signals such as skin temperature, oxygen saturation, heart rate, and inertial motion. System validation was performed through rigorous laboratory calibration against reference impedances and subsequent in vivo testing on a human volunteer in an isolated room with no external stimuli whatsoever. The laboratory results indicated high-precision performance, with the mean absolute errors of the measurements being below 3 Ω in modulus and 0.2° in phase across a wide range of frequencies, from 1 kHz to 200 kHz. Preliminary in vivo benchmarks confirm the functionality of the device. These findings demonstrate that the MsW2-v2 successfully bridges the gap between high accuracy and wearable form factors, bringing us to the conclusion that this device could serve as a viable, scalable solution for real-time physiological measurements and biomedical signal monitoring.