Mechanical Energy Harvesting System from the Human Arm Movement for Continuous Blood Pressure Measurement

In this article, an approach to harvesting electrical energy from a mechanically excited piezoelectric element has been described. Three PMN-xPT compositions were used with x taking the values of 0.31, 0.33 and 0.35, in order to study the most important properties of piezoelectric PMN-PT in energy harvesting. This study uses a detailed analysis of three Relaxer (1-x)PMN-xPT ceramic compositions, with an emphasis on the influence of content on piezoelectric, dielectric, and electromechanical characteristics. Prototypes have been made and characterized, validating these energy thresholds. From this comparative analysis between the three compositions, it was found that PMN-35PT has the highest recoverable energy density. On the other hand, the pressure change in the radial artery was calculated using the pressure sensitivity of the sensor and systolic and diastolic characteristic points in the pressure pulse wave (PPW). The results show that piezoelectric, dielectric, and electromechanical properties are all directly associated with chemical composition, and that the examined ceramics outperform their PZT counterparts, making them very suitable for energy harvester systems and sensing device applications. Therefore, the structure developed is an external patch of 5x3cm², placed on the arm and able to recover 3.46 mW for PMN-35PT, during human walking. Results indicate that the suggested method demonstrated reliable systolic blood pressure (SBP) accuracy .The technology has the potential to be used for long-term continuous blood pressure monitoring. The piezoelectric sensor was placed on the skin above the radial artery and measured for 10 sec to obtain the continuous pressure waveform.