Piezoelectric AlN energy harvesters for wireless autonomous transducer solutions

Piezoelectric energy harvesters with aluminum nitride (AlN) are fabricated by micromachining. Devices with different size and mass were fabricated. The devices were packaged by a top and bottom glass wafer with cavities of 200mum to prevent excessive displacements. The devices are characterized on a shaker by applying an oscillation as mechanical input and measuring the power dissipated in a resistive load. A power output was generated of ~10muW for an acceleration of 8g at the resonance frequency of 1155Hz. The power generation for AlN is comparable with lead zirconate-titanate (PZT), despite the much lower piezoelectric constants. This makes AlN a very suitable material for energy harvesters due to its easier processing.