Quality and Damping Factors Optimization Using Taguchi Methods in Cantilever Beam Based Piezoelectric Micro-Power Generator for Cardiac Pacemaker Applications

Abstract

Piezoelectric Micro-Power Generator (PMPG) can produce electrical power as a result of piezoelectric effects. Moreover, producing self-powering devices, especially in small electronic devices with low power requirements such as cardiac pacemakers is one of the objectives of the study. This paper optimizes the quality and damping factors for PMPG by using the Taguchi optimization method instead of a trial and error approach. Eight physical control parameters with three levels, including PMPG layer materials and dimensions are selected in order to study the influence of each parameter of PMPG quality and damping factors. Level eighteen Orthogonal arrays is based on signal-to-noise ratio which is conducted and confirmed by using analysis of variance in determining the PMPG with the best quality and damping factor.18 experiments are conducted with three trials using COMSOL Multiphysics software ver. 5.4 for each one. The PMPG maximum quality factor, the lower damping factor, and the highest efficiency are designed at 1.35 Hz, which is equivalent to 81 beats per min. Both Taguchi and the analysis of variance results conclude that the highest PMPG physical control parameters affect the quality and damping factors at 1.35 Hz from higher to lower order as follows: insulator width of 0.12 mm, 0.2 mm piezoelectric layer width, 20 µm of insulator thickness, 2.5 mm of proof mass thickness, piezoelectric material of PZT5A, piezoelectric layer thickness of 60 µm, proof mass material of aluminum, and 5 mm proof mass length respectively. COMSOL Multiphysics is used again to study the PMPG with the best parameters, the PMPG resonates at 1.35 Hz, 5.78 Hz, 7.61 Hz, 32.54 Hz, 424.21 Hz, and 448.59 Hz respectively with a different mode of deflections by using Eigen’s frequency analysis. The high electric field, the electric energy density, and hence the output power are produced at first resonance frequency at 1.35 Hz in the range of 0.5-2.5 Hz by using frequency response analysis. Transient analysis is conducted at 1.35 Hz, which shows that the PMPG reaches the steady-state after seven seconds of sinusoidal signal excitation with quality factor of 166.67 and damping factor of 0.003. This improves that PMPG works nearly at no damping system and keeps oscillating for a long time before stopping for a single excitation, which opens the door widely in front of fabricating self-powered devices that have been working for a long time, which make them suitable to replace lithium iodide battery in cardiac pacemakers
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