Increasing the Sensitivity of Piezoelectric Pulse Wave Sensors for Pulse Wave Propagation Measurement

The use of piezoelectric film for pulse wave measurement is advantageous in terms of power consumption, but it has limitations in terms of sensitivity and noise resistance. This letter described a high-sensitivity pulse wave sensor that used a piezoelectric film. Furthermore, we proposed a 3-D gel structure to improve the sensor's skin contact condition and measurement sensitivity through structural innovations. Our approach was to increase the strain of the piezoelectric film by utilizing a structure with a tapered rate, which increased the sensitivity of the sensor structure. The subject was a healthy adult male (24 years old). We also fabricated a prototype pulse wave sensor with the proposed structure and continuously measured pulse waves at multiple locations on the radial artery of the wrist. Through signal processing, we were able to obtain measurement data that were effective for monitoring pulse wave propagation and showed that fluctuations in pulse wave velocity could be detected.