Pacemakers are implantable biomedical devices that regulate the pacing of the heart. However, The lithium-ion battery that it operates on only contains a lifespan of approximately 5-7 years, requiring the patient to undergo a surgical procedure for the replacement of the battery. As this increases the potential risk of infection, this project utilized an alternative source of energy: piezoelectrics, specifically the lead zirconate titanate (PZT) material. Since piezoelectrics generate voltage when they undergo mechanical stress, also known as the piezoelectric effect, they were used to construct a power harvester that would operate based on the vibrational frequency of the heart to provide power output for the pacemaker for at least a time period of 10 years before the piezoelectric deteriorates. Three different prototype designs of piezoelectric materials were made through CAD using the SolidWorks software where each design had a contrasting geometry to the conventional rectangular piezoelectric. The prototypes were then imported to the COMSOL Multiphysics software for its simulation and were tested alongside capacitors, resistors, and bridge rectifiers with varying amounts of stress that emulate the vibrational frequency that would be acquired from the heart, cyclic loadings, and loading frequencies for optimized power output, minimized degradation ratio, and minimized volume. The output voltage exceeded the amount of voltage required by a pacemaker: 0.1-15 volts and The degradation ratio was higher than 0.8, indicating that the power harvester lost only 20% efficiency in outputting power over its 10+ year lifespan, deeming it to be suitable to work alongside a lithium-ion battery. As this design is a low-frequency power harvester, it can be utilized for low-application devices that also run on lithium-ion batteries.

Engineering Need

Engineering Goal

More than three million people in the United States are diagnosed with Arrhythmia, a condition where the pacing of the heartbeat becomes abnormal due to the insufficient electrical impulses being provided by the heart (Bhatia, 2018). To resolve this issue, pacemakers have been considered as the main form of treatment for the reduction of symptoms, with over 200,000 devices being implanted every year just in the United States (Bhatia, 2018). The device itself is highly effective in functionality, however the predicament is the lifespan of this biomedical device. With a battery life of only 5-7 years, patients are required to undergo surgery once the battery is drained out, posing potential risks to their physical health such as infection at the site of implant, blood clots (thromboembolism), and collapsed lungs (Mulpuru et al., 2017). The proposed plan is to build a piezoelectric framework that would be able to sustain the lifespan of a pacemaker for an extended period.

This project conducted all design, development, and testing computationally. The design prototypes for the piezoelectric PZT plate were designed using Computer-Aided Design (CAD) using the SolidWorks software. The design protypes were tested and analyzed through the COMSOL software, which is a software utilized for Multiphysics simulation. Within COMSOL, the micro electromechanical systems (MEMS), computational fluid dynamics (CFD), and structural mechanics modules were used to test and analyze the piezoelectric power harvester. In order to apply certain characteristics to the power harvester, the Solid Mechanics, Electrostatics, and Electrical Circuit physics were applied.

Figure 1

Load in Newtons provided by the Vibrational Frequency of the Heart

Figure 2

Graph of Output Voltage

Figure 3

Rate of Voltage Degradation from Power Harvester

Figure 4

Graph of Eigenfrequency based on Varying Compression Levels