Basic Study on Non-contact Pulse Transit Time Estimation in Daily Life Using Micro-wave and Image Sensor

Mototaka YOSHIOKA  

D - Abstracts of IEICE TRANSACTIONS on Information and Systems (Japanese Edition)   Vol.J101-D   No.2   pp.395-404
Publication Date: 2018/02/01
Online ISSN: 1881-0225
Type of Manuscript: Special Section PAPER (Special Section on Human Communication)
pulse transit time,  microwave,  image sensor,  noncontact vital sensing,  

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This study proposes a new approach for non-contact based pulse transit time (PTT) measurement using microwave and image sensors. The PTT, which is the time difference between the heartbeat and the pulse peak arrival taken at a certain body location, is considered as a significant diagnostic index for conditions such as blood pressure and arterial stiffness. In this study, the microwave sensor detects heartbeats using reflected wave signal from a subject's chest, and the image sensor obtains pulse-arrival times using a subject's face image sequences. By temporally synchronizing these sensors, the proposed system calculates the time difference between a heartbeat and a pulse, thus allowing PTT to be remotely obtained. In a basic experiment, the PTTs obtained using the proposed system were correlated with contact-based PTTs in sixteen human participants, and a high correlation coefficient of 0.69 (p < 0.01) was obtained. The results indicated the potential viability for widespread use of the proposed method for non-contact-based PTT measurement.