Harvesting Energy from vibrations with the piezoelectric effect

Abstract

Modern internet–based technologies require devices that can generate, acquire, and compute data. Typically, these devices rely on conventional batteries, which limit device size, lifespan, and introduce maintenance costs due to replacements. A promising alternative is using piezoelectric energy harvesters, which convert mechanical stress into voltage via the piezoelectric effect. These harvesters need to be activated by external vibrations, but most current systems operate in a frequency range of 50 to 300 Hz. However, ambient vibrations often occur at lower frequencies (5 to 40 Hz) and are not constant,making it challenging to harvest energy efficiently when the frequency mismatch occurs.
The objective of this research is to develop a design that can harvest energy from a broad range of low and non–constant frequencies and develop a testing methodology for its dynamic characterization that represents a real–world scenario, by using square wave and noise excitation. The proposed design is based on the frequency up–conversion principle. The design features a driving oscillator, a bi–stable oscillator that resonates at low frequencies and collects energy during its snap–through motion. The generating oscillator, on the other hand, resonates at higher frequencies and contains the piezoelectric material. The energy harvesting is achieved by the transfer of energy from the driving to the generating oscillator.
The dynamic characterization of the design resulted in several findings. The proposed design can up–convert frequency by a factor of 208 and harvest energy at low input vibration (0.1–20 Hz) and noise excitation (0–300 Hz). Overall this research contributes to the field of energy harvesting by introducing a new design that can harvest energy fromambient vibrations and a new testing procedure that replicates a real–world scenario.