FABRIC-INTEGRATED SENSORS AND BIOELECTRODES FOR WEARABLE HEALTH MONITORING: DESGIN, DEVELOPMENT, & APPLICATION

Author

S. Zohreh Homayounfar, University of Massachusetts AmherstFollow

Author ORCID Identifier

https://orcid.org/0000-0001-8980-8265

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemistry

Year Degree Awarded

2023

Month Degree Awarded

September

First Advisor

Trisha L. Andrew

Subject Categories

Biomedical Devices and Instrumentation | Materials Chemistry | Other Chemistry | Polymer and Organic Materials

Abstract

The integration of wearable sensors into everyday garments enables seamless collection of human motion and physiological signals in natural environments. However, there is a significant lack of reliable sensors meeting these longitudinal monitoring requirements. This thesis addresses this gap by designing fabric/thread-based sensors: PressION, a pressure sensor capable of accurately measuring physiological metrics and motion information from loose-fitting garments, and tAgTrode, a groundbreaking thread-based hydrogel electrode for sensing electrical physiological signals. To begin, PressION is introduced, an all-fabric pressure sensor with desirable sensitivity across a wide range of pressures, including subtle dynamic pressures like heartbeats and large static pressures like body weight. The second generation of PressION utilizes oxidative chemical vapor deposition (oCVD) of poly(3,4-ethylenedioxythiopene):chloride PEDOT:Cl and leverages the natural three-dimensional hierarchical structure of cottonballs to create a wash-stable, environment-insensitive fabric-based pressure sensor. This sensor can be seamlessly integrated into garments to extract a variety of physiological metrics through pressure signals. In the subsequent phase, a thread-based hydrogel electrode called tAgTrode is developed for sensing biopotential signals, including electrooculography (EOG). Initiated chemical vapor deposition (iCVD) creates an ionically-conductive composite hydrogel grafted to the embroidered thread layer. This hydrogel exhibits resistance to hydration-dehydration cycles, wash stability, and high water-retention capacity, making it suitable for long-term biopotential monitoring applications. PressION and tAgTrode are integrated into a fabric-based eyemask, Chesma, enabling longitudinal capturing of eye movement and arterial pulse simultaneously. Lastly, longitudinal electroencephalography (EEG) monitoring of neural signals is addressed by developing PhyHoop, a headworn device equipped with the second-generation thread-based hydrogel electrode. PhyHoop enables long-term monitoring of EEG signals from the frontal lobes of the brain. The hydrogel-based electrode exhibits significantly lower skin-electrode contact impedance (~70% drop) and higher signal power after extended monitoring (~200 times higher after 6 hours) compared to standard goldcup electrodes. Through collaborative and multidisciplinary work, these fabric-based pressure sensors and bioelectrodes are incorporated into various platforms such as PhyMask, Phyjama, and FabToy for user studies and data analysis. The superior performance of these sensors compared to gold-standard methods and commercial devices demonstrates their potential for widespread adoption in daily life, serving human health and point-of-care applications.

DOI

https://doi.org/10.7275/35719193

Recommended Citation

Homayounfar, S. Zohreh, "FABRIC-INTEGRATED SENSORS AND BIOELECTRODES FOR WEARABLE HEALTH MONITORING: DESGIN, DEVELOPMENT, & APPLICATION" (2023). Doctoral Dissertations. 2895.
https://doi.org/10.7275/35719193 https://scholarworks.umass.edu/dissertations_2/2895