Analysis and experimental validation of the figure of merit for piezoelectric energy harvesters

Analysis and experimental validation of the figure of merit for piezoelectric energy harvesters

Deutz, D.B. (TU Delft Novel Aerospace Materials; University of Southern Denmark)
Pascoe, J.A. (TU Delft Structural Integrity & Composites; Imperial College London)
Schelen, J.B.J. (TU Delft EMSD EEMCS Project engineers)
van der Zwaag, S. (TU Delft Novel Aerospace Materials)
de Leeuw, D.M. (TU Delft Novel Aerospace Materials)
Groen, W.A. (TU Delft Novel Aerospace Materials; TNO)

2018-05-01

Piezoelectric energy harvesters are at the front of scientific research as enablers of renewable, sustainable energy for autonomous wireless sensor networks. Crucial for this disruptive technology is the achievable output power. Here we show, analytically, that the maximum output energy per unit volume, under a single sinusoidal excitation, is equal to 1/(4 - 2k²) × 1/2dgX², where k² is the electromechanical coupling coefficient, d and g are the piezoelectric charge and voltage coefficient, respectively, and X is the applied stress. The expression derived is validated by the experimentally measured output energy for a variety of piezoelectric materials over an unprecedented range of more than five orders of magnitude. As the prefactor 1/(4 - 2k²) varies only between 1/2 and 1/4 the figure of merit for piezoelectric materials for energy harvesters is not k², as commonly accepted for vibrational harvesters, but dg. The figure of merit does not depend on the compliance, or Young's modulus. Hence we argue that commonly used brittle inorganic piezoelectric ceramics can be replaced by soft, mechanically flexible polymers and composite films, comprising inorganic piezoelectric materials embedded in a polymer matrix.

http://resolver.tudelft.nl/uuid:3ebce2f3-e2d8-433c-bbcd-684e0835c14b

https://doi.org/10.1039/c8mh00097b

2018-09-01

2051-6347

Materials Horizons, 5 (3), 444-453

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2018 D.B. Deutz, J.A. Pascoe, J.B.J. Schelen, S. van der Zwaag, D.M. de Leeuw, W.A. Groen