Flexible PCB Failures From Dynamic Activity and Their Impacts on Bioimpedance Measurements: A Wearable Case Study

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Date
2021
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Journal ISSN
Volume Title
Publisher
IEEE
Abstract

Wearable health monitoring systems that collect data in free-living environments are becoming increasingly popular. Flexible printed circuits provide a commercially available option that can conform to the shape of a wearable system and support electronic sensing and flexible interconnect. However, repetitive dynamic activity can stress and damage the interconnect of flexible PCBs which degrades data quality. This case study evaluated the performance of flexible PCBs providing interconnect between electrodes and sensing electronics for tissue bioimpedance measurements in a wearable system. Resistance data (1 kHz to 128 kHz) was collected from localized knee tissues of 3 participants using the wearable design with flexible PCBs over 7 days of free-living. From electrical and optical inspection after use trace cracking of the flexible PCBs occurred, degrading tissue resistances reported by the wearable system. Exploration of these results advances understanding of how flexible PCBs perform in free-living conditions for wearable bioimpedance applications.

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Keywords
Flexible printed circuits, Atmospheric measurements, Wearable computers, Integrated circuit interconnections, Bioimpedance, Inspection, Particle measurements, wearable sensors, failure analysis, trace cracking, bioimpedance, TISSUE BIOIMPEDANCE, LOW-COST, ARRAY, Engineering, Electrical & Electronic
Citation
Critcher, S., & Freeborn, T. J. (2021). Flexible PCB Failures From Dynamic Activity and Their Impacts on Bioimpedance Measurements: A Wearable Case Study. In IEEE Open Journal of Circuits and Systems (Vol. 2, pp. 732–742). Institute of Electrical and Electronics Engineers (IEEE). https://doi.org/10.1109/ojcas.2021.3122369