Abstract
Energy generation technologies that use piezoelectric materials as uninterrupted power supplies are one of the most practical solutions of low-power wireless sensor network. The piezoelectric generator collects mechanical energy from the environment and transforms it into electricity to supply to microelectronic devices. Thus, these alternative energy sources can reduce the consumption of batteries, thereby reducing environmental pollution. Piezoelectric materials can work in the bending, compression, and shear modes, which are named as d31, d33, and d15 modes, respectively. In this study, a piezo stack which worked in d31 mode has been designed and integrated into an energy harvesting pedal. A novel compliant amplifying mechanism has to be designed to amplify the input load so that the high-stiffness piezoelectric stack can achieve a large energy output at a lower input force. This compliant mechanism has been designed by the pseudo-rigid-body and topology optimization methods. The amplification ratios of different sized flexible amplification mechanisms are calculated through the finite element analysis and validated by experiments. Finally, a pedal generator has been made and the test results show that the collected electricity can effectively drive a low-power microcontroller, sensor, and other devices of these kinds.
Highlights
Energy harvesting technologies that can collect energy from the surroundings and store it for small autonomous devices have been making rapid progress recently
The piezoelectric transducer has the advantages of simple structure, easy miniaturization, superior energy density, and no-bias voltage requirement, and has broad prospects in the energy harvesting applications
Piezoelectric materials are proposed for use in energy harvesting devices
Summary
Energy harvesting technologies that can collect energy from the surroundings (e.g. solar power, thermal energy, wind energy, mechanical energy, and so on) and store it for small autonomous devices have been making rapid progress recently. Each piezoelectric material can operate as an energy generator in three types of coupling modes, which are named as d31, d33, and d15 modes.[8] As showed, the most commonly used piezoelectric harvester is the d31 mode in which normal strain is perpendicular to the direction of the electric field. It has several advantages compared with a rigid mechanism and can be fabricated in a simplified way, since it consists of fewer parts and needs less assembly work This compactly structured mechanism can reduce and even avoid the connection of kinematic joints, reducing abrasion and clearance, and avoiding lubrication.[9] There are mainly two ways to design the compliant mechanism: the pseudorigid-body (PRB) method and the topology optimization method.[10] The PRB model is a set of diagrams and formulas, which describes the corresponding relationship between the movement and strength of elastic elements and rigid structures. The piezoelectric material used in this article is PZT4 piezoelectric ceramic material, and its material
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