Pulse monitoring by sol-gel composite flexible piezoelectric sensors

Pulse monitoring at home would be effective to maintain personal health without increasing medical cost and development of the low cost pulse monitoring sensor is desired. Conventional PVDF sensors were too flexible so that ringing effect might not be ignorable and it would resulted in low signal to noise ratio (SNR). Piezoelectric films made by sol-gel composite itself was flexible and it could have less ringing effect so that SNR could be higher. PZT/PZT films with evaporated aluminum top electrode were fabricated onto various thickness stainless steel substrate in order to optimize the device design. For d₃₃ measurement result, piezoelectric film thickness correlated highly with d₃₃ value, whereas substrate thickness showed poor correlation. Pulse measurements on the wrist were attempt by PZT/PZT piezoelectric film sensors and PVDF film sensor and in several configurations, PZT/PZT sensors presented higher SNR than that of PVDF sensor.