improving power density of piezoelectric vibration-based energy scavengers

Vibration energy harvesting with piezoelectric materials currently generate up to 300 microwatts per cm^2, using it to be mooted as an appropriate method of energy harvesting for powering low-power electronics. one of the important problems in bimorph piezoelectric energy harvesting is the generation of the highest power with the lowest weight. in this paper the effect of the shape and geometry of a bimorph piezoelectric cantilever beam harvester on the electromechanical efficiency of the system is studied. an analytic model has been presented using rayleigh cantilever beam approximations for piezoelectric harvesters with tapered bimorph piezoelectric cantilever beam. in order to study the effect of a cantilever beam length and geometry on the generated voltage, finite element simulation has been performed using abaqus. design optimization has been used to obtain the maximum output power and tapered beams are observed to lead to more uniform distribution of strain in the piezoelectric layer, thus increasing efficiency.