Open-circuit direct piezoelectric coefficients g31 of bi-axially stretched PVDF and chiral PLLA are reported. This measure is decisive for sensor, generator and energy harvesting applications. We use an in-situ method with contactless voltage measurement during a conventional tensile-test, greatly improving measurement precision (error less than 10%).

In this paper, harvesters coupling magnetostrictive and piezoelectric materials are investigated. The energy conversion of quasi-static magnetic field variations into electricity is detailed. Experimental results are exposed for two macroscopic demonstrators based on the rotation of a permanent magnet. These composite/hybrid devices use both piezoelectric and magnetostrictive (amorphous FeSiB ribbon or bulk Terfenol-D) materials. A quasi-static (or ultra-low frequency) harvester is constructed with exploitable output voltage, even in quasi-static mode. Integrated micro-harvesters using sub-micron multilayers of active materials on Si have been built and are currently being characterized.