Methodology For Design of Broadband Low Frequency Piezoelectric Energy Harvester

A significant impediment in the deployment of vibration-based energy harvesting devices has been the limitation that most of the low frequency transducers, usually in the form of unimorph or bimorph cantilever beams, extract energy in a very narro bandwidth around the transducer's fundamental frequency. In such devices, slight deviation from the fundamental frequency causes a significant reduction in the level of harvested power, in some cases by orders of magnitudes. Additionally, most of the current research efforts in the design of piezoelectric energy harvesters at the microscale have challenges in achieving a low resonance frequency below 100 Hz. Here a design methodology is described for overcoming these challenges of conventional resonant piezoelectric energy harvesters and novel low-frequency wide bandwidth harvesters are proposed and validated. We have designed a zigzag piezoelectric energy harvester that consists of a steel substrate and piezoelectric layers (unimorph). This harvester responds to the direct vibration excitations. Experimental measurements were performed to determine the effects of the tip mass and electrical load resistance on the performance of this harvester. To design the low-frequency and broadband energy harvester, a novel technique was established that utilizes a second degree-of-freedom with resonant frequency near that of the natural frequency of the harvester.
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Grant Brewer
Senior Licensing Associate
Virginia Tech Intellectual Properties, Inc.
(540) 443-9218
Abdessattar Abdelkefi
Nathan Sharpes
Shashank Priya
Muhammad Hajj