Fabrication of Piezoelectric Vibration Power Harvester using Bulk PZT
Piezoelectric energy harvester with high output and low resonant frequency is required in wireless sensors and portable devices. It can be fabricated by bonding of the bulk PZT ceramics with excellent piezoelectric properties to the Si wafer. Firstly, the basic design principles of piezoelectric energy harvester were analyzed. Then, the novel process flow to manufacture piezoelectric energy harvester using bulk PZT was explored. Using 2µm Au layer as the bonding layer, the bulk PZT was bonded to Si wafer at the temperature of 5500C for 2 hours. With the lapping technique, the thickness of bulk PZT is reduced from 300µm to 60µm. KOH was used to etch the backside of Si from 500µm to 20µm as the supporting layer of the piezoelectric beam. The last procedure was to dice the wafer into many cantilevers with different length or width. One of PZT piezoelectric cantilevers was tested using a mechanical shaker, by applying a sinusoidal oscillation at different frequencies. The resonant frequency is 815 Hz, and the voltage output is around 632 mV at 0.5g. The result shows that the sample has excellent ability to harvest energy of vibration and the novel bonding technology is quite feasible.
J. Sun et al., "Fabrication of Piezoelectric Vibration Power Harvester using Bulk PZT", Key Engineering Materials, Vol. 483, pp. 631-634, 2011