This paper describes a non-contact heart rate monitoring system using a microwave Doppler sensor. It can achieve better usability than conventional heart rate sensors, which require direct skin contact. The objective of this work is to detect an instantaneous heart rate using this non-contact system. The instantaneous heart rate can contribute to prevent heart disasters and to detect mental stress state. However, the Doppler sensor system is very sensitive and it can be easily contaminated by a body motion artifact including breathing. To address this problem, we introduce time frequency analysis with short window length. The heart rate extraction performance with various parameters is evaluated using a measured Doppler sensor output with 4 subjects. The proposed method achieves 4.5-ms RMS error with 50-cm distance for heart rate extraction from 60 s duration data.
['Daichi Matsunaga', 'Shintaro Izumi', 'Hiroshi Kawaguchi', 'Masahiko Yoshimoto']
Non-contact Instantaneous Heart Rate Monitoring Using Microwave Doppler Sensor and Time-Frequency Domain Analysis