Basic Overview of Piezoelectric Materials in Energy Harvesting
Energy harvesting is approaching an interesting technological juncture wherein the power requirements for electronic devices have been reduced while at the same time the efficiency of energy harvesting devices has increased. Out of various
possible energy harvesting technologies, piezoelectric vibration energy harvesting has emerged as a method of choice for powering meso-to-micro scale devices. Piezoelectric materials and transducers can be designed to handle a wide range of input frequencies and forces allowing for energy harvesting to occur.
During vibration energy harvesting, piezoelectric materials convert mechanical strain into an electrical charge or voltage via the direct piezoelectric effect. The power output of a particular piezoelectric energy harvester depends upon intrinsic and extrinsic factors. Intrinsic factors include the frequency constant of the piezoelectric element, piezoelectric and mechanical properties of the material, and the temperature and stress dependence of the physical properties. Extrinsic factors comprise of the input vibration frequency, acceleration of the base/host structure, and the amplitude of the excitation.
Cantilever geometry is one of the most widely used architectures in piezoelectric energy harvesters, especially for mechanical energy harvesting from vibrations, because, a large mechanical strain can be produced within the piezoelectric material during vibration. The majority of the piezoelectric energy harvesting 
devices developed employ a unimorph (one layer of piezoelectric material bonded to a non-piezoelectric layer) or a bimorph (two layers of piezoelectric material bonded to a non-piezoelectric layer) with a cantilever design. Bimorph piezoelectric cantilevers are more commonly used in piezoelectric energy harvesting studies than unimorphs, because, the bimorph structure doubles the energy output without any significant increase in the device volume.
devices developed employ a unimorph (one layer of piezoelectric material bonded to a non-piezoelectric layer) or a bimorph (two layers of piezoelectric material bonded to a non-piezoelectric layer) with a cantilever design. Bimorph piezoelectric cantilevers are more commonly used in piezoelectric energy harvesting studies than unimorphs, because, the bimorph structure doubles the energy output without any significant increase in the device volume.Piezoelectric materials for use in energy harvesting applications can be divided into four different categories: ceramics, single crystals, polymers, and composites. Generally, piezoelectric ceramics are used as the piezoelectric material in energy harvesting devices due to their low cost, good piezoelectric properties, and ease of integration into energy harvesting devices.
If you’re interested in learning more about energy harvesting using piezoelectric materials read the full article on the Principles of Piezoelectric Energy Harvesting APC’s blog or Contact an APCI Representative today!
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