Improvement of noncontact heart rate measurement by millimeter-wave radar utilizing respiratory components of biological signals

Vital signs are important indicators for assessing an individual's health status, and technologies that measure the vital signs of patients and caregivers using electronic devices and monitor their behavior are gaining increasing attention. Texas Instruments Inc. has developed a noncontact vital sign measurement algorithm that utilizes millimeter-wave (mmWave) radar technology. This algorithm is capable of detecting clearer heartbeat signals using an infinite impulse response (IIR) filter to reduce and eliminate interference from respiration. However, the heart rate component in biological signals is inherently weak and susceptible to noise interference during measurement, necessitating advanced technical solutions to improve the measurement accuracy. This study proposes a novel method to enhance measurement accuracy by integrating the directional and temporal characteristics of chest movements resulting from respiration and heartbeats rather than suppressing or removing the influence of respiration as in the conventional method. The experimental results show that the error rate of the measurement results obtained by the proposed method is 0.9% at its lowest, achieving a reduction of approximately 40% compared with the error rate obtained by the conventional method.