mm-Wave Radars for Healthcare Monitoring

Vital signs detection is important for human health status assessment, and timely accurate detection is of great significance for modern health care and intelligent medical applications. Conventional contact detection may restrict the behaviors of users, cause additional burdens, and render users uncomfortable. In recent years, noninvasive health monitoring technology has attracted a lot of interest. With the advantages like possibility of long-term monitoring, no need for preparation of electrodes or other sensors, and non-contact measurement, Doppler Radar Sensor (DRS) has been widely studied to detect the human vital signs such as respiration and heartbeat. However, the amplitude of heart motion and pulse motion is µm-level ultraweak motion, so a high-sensitivity and high-linearity Doppler radar sensor working on appropriate frequency is needed to provide accurate displacement measurement of the human vital signs. Furthermore, the obtained original radar signal is a mixture of multiple human motion signals, a suitable signal separation method should be used to acquire the separated human vital signs. In this workshop presentation, a K-band 24GHz continuous wave DRS was then designed which is able to detect µm-scale motions. Based on the high-performance DRS, a high-accuracy physiological signal extraction algorithm has been developed. It realizes accurate acquisition of human Doppler Cardiogram (DCG) which describes the human heart’s mechanical activities and provides the timing information of the P-wave, QRS-waves, and T-wave in ECGs. Meanwhile, a FIR filter is used to obtain the respiration signal and an autocorrelation computation is utilized to reduce the effect of environment noise. And the proposed DRS can also accurately detect the wrist pulse waveform for blood pressure measurement. In conclusion, the Doppler radar technology including the hardware design and signal processing algorithm, has promising performance of human vital signs detection and has great potentials in extended applications such as hospitalization, personal daily healthcare.