توسعه برداشتگر انرژي سيسموكارديوگرافي براي ايمپلنت هاي ضربانساز قلب خودتوان

This thesis presents the electrical eva‎luation of piezoelectric energy harvesting systems for low-power implantable medical devices, particularly cardiac pacemakers. Due to the inherent limitations of conventional batteries, including finite capacity an‎d the need for periodic replacement surgeries, developing alternative power sources is essential. Mechanical energy from continuous cardiac activity is investigated as a potential energy source. Two interface circuit topologies, a full-bridge rectifier an‎d a voltage doubler, are compared under identical conditions. An equivalent electrical model of the piezoelectric harvester was implemented in circuit simulation software. Simulation parameters included an excitation voltage of 1.5 V, frequency of 100 Hz, internal capacitance of 50 E, an‎d load resistance of 100 Q. eva‎luation metrics comprised output voltage, power, efficiency, voltage ripple, an‎d transient behavior. Results demonstrate that the voltage doubler significantly outperforms the full-bridge rectifier across all metrics. DC output voltage increased from 0.748 V to 1.497 V, representing approximately a twofold improvement. Output power rose from 5.59 μW to 22.41 μW, achieving a fourfold increase. Conversion efficiency improved from 6.32% to 25.35%, while output voltage ripple decreased substantially from 19.8% to 5.3%. Furthermore, the voltage doubler reached 1.8 V within 72.4 ms, whereas the full-bridge rectifier never attained this threshold under the same loading conditions. The superior performance of the voltage doubler is attributed to its charge-pump mechanism, which stores energy in an intermediate capacitor an‎d transfers it to the output, effectively boosting voltage levels. Diode voltage dro‎ps in the full-bridge rectifier constitute the primary loss mechanism, particularly at low voltage amplitudes. This finding underscores the critical role of interface circuit topology in determining usable energy in low-power harvesting systems. While this research is conducted within a simulation framework, the results indicate the strong potential of voltage doubler circuits for implantable medical applications. Future work should focus on physical prototype fabrication, experimental validation, real cardiac mechanical excitation analysis, an‎d maximum power point tracking circuit design to realize a fully functional self-powered medical device.

مينا اميري

احمدرضا تابش

محمد داورپناه جزي , الهام محمودزاده