A gold nanowire-integrated soft wearable system for dynamic continuous non-invasive cardiac monitoring.

ABSTRACT

Blood pressure (BP) is a cardiovascular parameter which exhibits significant variability. Whilst continuous BP monitoring would be of significant clinical utility. This is particularly challenging outside the hospital environment. New wearable cuff-based and cuffless BP monitoring technologies provide some capacity, however they have a number of limitations including bulkiness, rigidity and discomfort, poor accuracy and motion artefact. Here, we report on a lightweight, user-friendly, non-invasive wearable cardiac sensing system based on deformation-insensitive conductive gold nanowire foam (G-foam) and pressure-sensitive resistive gold nanowire electronic skin (G-skin). The G-foam could serve as a new soft dry bioelectrode for electrocardiogram (ECG) monitoring; a new soft button-based G-skin design could avoid manual holding for continuous pulse recording. They could be integrated seamlessly with everyday bandage for facile wireless recording of ECG and artery pulses under real-word dynamic environments including walking, running, deep squatting, and jogging. Further machine learning algorithm was developed for estimation of systolic and diastolic BP, showing comparable accuracy to commercial cuff-based sphygmomanometer. The measured dynamic BP changes correlated well with the volunteer's daily activities, indicating the potential applications of our soft wearable systems for real-time diagnostics of cardiovascular functions in complex dynamic real-world setting.