Contactless, Battery-free, and Stretchable Wearable for Continuous Recording of Seismocardiograms

Seismocardiography (SCG) is the technique to measure microscale vibrations of the chest, which is closely related to the mechanical activity of the heart. To date, only a few studies have reported technical solutions to remotely measure SCG signals with soft electronics using stretchable, piezoelectric thin films. In this study, however, we demonstrate a contactless wearable patch using a 28-μm-thick foil of the piezoelectric polymer polyvinylidene fluoride. As a technical advancement, we utilize near-field communication (NFC) technology to power the patch and to record the SCG data wirelessly. A separated electrocardiogram (ECG) is used as a reference. Our results show expected waveforms of the recorded SCG signals with good signal-to-noise ratios and a close correlation between SCG and ECG recordings. The SCG technique adds an additional tool for cardiac monitoring, which is tightly associated with an ECG. The SCG method could be combined with other techniques in wearable on-skin electronics with multiple functionality for advanced cardiovascular monitoring.