PressION: An All-Fabric Piezoionic Pressure Sensor for Extracting Physiological Metrics in Both Static and Dynamic Contexts

Abstract

The strategy of detecting physiological signals and body movements using fabric-based pressure sensors offers the opportunity to unobtrusively collect multimodal health metrics using loose-fitting, familiar garments in natural environments. (A. Kiaghadi, S. Z. Homayounfar, J. Gummeson, T. Andrew, and D. Ganesan, Proc. ACM Interact. Mob. Wearable Ubiquitous Technol., 3, 1–29 (2019)). However, many sensing scenarios, such as sleep and posture monitoring, involve an added static pressure from exerted body weight, which overpowers weaker pressure signals originating from heartbeats, respiration and pulse and phonation. Here, we introduce an all-fabric piezoionic pressure sensor (PressION) that, on account of its ionic conductivity, functions over a wide range of static and dynamic applied pressures (from subtle ballistic heartbeats and pulse waveforms, to larger-scale body movements). This piezoionic sensor also maintains its pressure responsivity in the presence of an added background pressure and upon integration into loose-fitting garments. The broad ability of PressION to record a wide variety of physiological signals in realistic environments was confirmed by acquiring heartbeat, pulse, joint motion, phonation and step data from different body locations. PressION’s sensitivity, along with its low-cost fabrication process, qualifies it as a uniquely useful sensing element in wearable health monitoring systems.