触覚センサを用いた無拘束瞬時心拍数測定方法の提案と検証

抄録

Heart rate is one of the biological rhythms and has fluctuating properties. This fluctuation is induced by various causes, and it is said that, by analyzing the fluctuation, useful information on the health state such as the stress index and prognosis of cardiovascular system can be obtained. However, because heart rates are usually measured with cumbersome sensor devices or electrodes, the measurement of instantaneous heart rate, which has equivalent information to heart rate variability, is also difficult to be conducted on a daily basis. To solve this problem, we are developing systems to detect instantaneous heart rate from output of a soft rubber-based tactile sensor put on a bed. We expect that information on heart beat is contained in pressure time series obtained from the tactile sensor. Using a signal processing technique called complex demodulation, the instantaneous frequency of the oscillation in the heart rate frequency range can be obtained from the pressure time series. To confirm that the detected instantaneous frequency coincides with the conventional instantaneous heart rate obtained from ECG, we measured ECG and pressure time series from the tactile sensor simultaneously, and compared the detected instantaneous frequencies using cross-correlations. The results were quite promising. This shows the possibility that we may be able to develop a nonrestraint health monitoring system using a tactile sensor. The system may record heart rate variability on a daily basis, and detect stress indices and symptoms of diseases. In this paper, we propose the instantaneous heart rate detection method from tactile sensor output, and show its promising experimental results.