A Compact Non-Contact Heart Sound Sensor Based on Millimeter-Wave Radar

A novel radar sensing system for non-contact and continuous detection of heart sound is proposed in this paper, which is a custom designed 120 GHz interferometric radar. The moving trajectory of the heart pulses can be accurately demodulated based on the radar signals, and thus the heart sounds can be reconstructed. Experiments have been carried out with electrocardiogram (ECG) and phonocardiogram (PCG) as reference. The results show the heart pulse signatures to an accuracy of micrometer level can be detected by the designed radar sensor, and the reconstructed heart sound can be visually and acoustically recognized. There is also a certain degree of similarity between the PCG signals and the heart sound signals reconstructed by the proposed radar sensor. The experimental results reveal the possibility for the proposed radar system as a heart sound sensor to be employed inside and outside the clinic, such as applications in the vast internet-of-things (IoT) and in-home health monitoring.