Wearable PZT Piezoelectric Sensor Device for Accurate Arterial Pressure Pulse Waveform Measurement

Abstract

Accurate, non-invasive, and wearable measurement of arterial pressure pulse waveforms is crucial for cardiovascular healthcare, yet remains challenging due to the lack of effective sensors and mounting methods. This study introduces highly sensitive, flexible PZT piezoelectric sensors and an optimized mounting method for accurate radial pulse waveform measurement in natural wrist positions. The sensors incorporate a PZT thin film directly fabricated on a flexible substrate with easily produced parallel-plate electrodes, requiring no poling treatment. The high-quality PZT films exhibit low charge leakage, enabling measurement even at 1 Hz. To ensure comfort and accuracy, a foam pad is used for optimal sensor mounting and investigate how its stress–strain properties affect pulse detection. The optimized sensor device captures waveforms closely matching those from a high-accuracy capacitive force sensor. Despite smaller size and lower mounting load, the sensors show four times the sensitivity of polyvinylidene fluoride sensors and successfully detect age-related changes in waveforms. Additionally, a deep learning model is developed to enable calibration-free conversion of sensor signals to blood pressure (BP), achieving a mean absolute error of 5.82 and 4.60 mmHg for systolic and diastolic BP. These results highlight the potential of this technology for effective cardiovascular monitoring in daily life.