Noncontact Cardiac Parameters Estimation Using Radar Acoustics for Healthcare IoT.

Novel use of radar acoustics for non-contact cardiac parameter estimation is presented as a potentially invaluable addition to Wireless sensor networks in Healthcare IoT. Here radar acoustics refers to the radar captured high frequency mechanical motion, beyond 20 Hz, on the skin surface induced by heart sound acoustic waves. Conventional radar based heart rate detection methods rely on detecting the heartbeat motion, around 1 Hz, while the unaddressed respiration motion coupling issue prevents consistent heartbeat estimation accuracy in the presence of stronger respiration interference, below 1 Hz. Another issue common to prior methods is the non-adaptive spectral filter design for separating heartbeat signal. As a consequence, these methods cannot be generalized to measurement spaces with high heartbeat variability as demonstrated in this study. To effectively address these limitations, a new heart rate detection method using radar is proposed to derive a high fidelity pulse template from the smoothed envelogram of heart sound measurements. What’s more, the feasibility study of radar heart sound based heart rate variability analysis is performed, in which inter-beat-internal is derived from the first and second heart sound signatures. To that end, automatic identification of heart sound signatures and signal denoising techniques are developed accordingly. Multiple validation experiments are conducted on human subjects. Our results imply that the new methodology effectively improves remote cardiac sensing performance using radar technology and presents an exciting opportunity to expand Healthcare IoT, improving patient experiences and outcomes.