Unconstrained Vital Sign Monitoring System Using an Aortic Pulse Wave Sensor.

This paper proposes a novel unconstrained monitoring system that measures heart and respiratory rates and evaluates autonomic nervous activity based on heart rate variability. The proposed system measures the aortic pulse waves (APWs) of a patient via an APW sensor that comprises a single microphone integrated into a mattress. Vital signs (i.e., heart rate, respiratory rate) and autonomic nervous activity were analyzed using the measured APWs. In an experiment with supine and seated participants, vital signs calculated by the proposed system were compared with vital signs measured with commercial devices, and we obtained the correlations of r > 0.8 for the heart rates, r > 0.7 for the respiratory rates, and r > 0.8 for the heart rate variability indices. These results indicate that the proposed system can produce accurate vital sign measurements. In addition, we performed the experiment of image stimulus presentation and explored the relationships between the self-reported psychological states evoked by the stimulus and the measured vital signs. The results indicated that vital signs reflect psychological states. In conclusion, the proposed system demonstrated its ability to monitor health conditions by actions as simple as sitting or lying on the APW sensor.

Unconstrained Monitoring of Biological Signals Using an Aortic Pulse Wave Sensor.

This paper proposes a system to extract biological signals from aortic pulse waves which are measured by a microphone type pulse wave sensor. Theproposed system enables extraction of three biological signals corresponding to respiratory rate, pulse pressure wave, and RR interval simply by sitting on the seat on which the sensor is laid. Experiment results demonstrated that the mean absolute errors between the signals measured by the proposed system and the conventional sensors are as low as 0.38 times per minute for the respiratory rate, 11.2 mmHg for the pulse pressure wave, and 16.6 ms for the RR interval. The proposed system thus may be applied to monitor the physiological state of a human subject to prevent accident caused by health condition.