A PIEZOPOLYMER FINGER PULSE AND BREATHING WAVE SENSOR

Pulse sensing is a convenient and efficacious way of aquiring important physiological information concerning the cardiovascular system. Finger pulse pickups can be employed in systems that measure blood pressure, heart rate and blood flow. This paper describe a new structure of polyvinylidene fluoride (PVDF) finger pulse and breathing wave sensor. Much consideration was given to take full advantage of the material's broad frequency response and to ensure a very low inferior-cut-off-frequency in the design of the following electronics as well as the sensor itself. The PVDF films used by the authors were stretched, poled and metallised on both surfaces. The surface extensional operation mode (31 mode) was adopted in the designing of the sensor. The packaging process of the sensor and the hybrid buffer electronics is the knotty point in the making of the sensor. The results of experimental measurements showed that the PVDF sensor can pick up breathing waves simultaneously with pulse waves. Spectral analysis of pulse recordings also showed interesting and enlightening results suggesting that messages about microcirculation and other cardiovascular activities could also be extracted. © 1990.