Wafer Level Fabrication of Vibrational Energy Harvesters using Bulk PZT Sheets

This paper presents a complete wafer level microfabrication process for the production of unimorph MEMS energy harvesters based on bulk PZT. Recently, piezoelectric harvesters designed to take advantage of the high quality piezoelectric properties of bulk PZT have been fabricated using local placement and bonding of individual PZT pieces and large proof masses at the chip level. With the process presented here, 16 piezoelectric energy harvesters have been fabricated in parallel at the wafer level by bonding a single bulk PZT sheet to a silicon wafer and processing the wafer with standard microfabrication techniques including an electrodeposition step to deposit a thick (> 200 mu m) nickel proof mass. The fabricated harvesters are able to generate an output power of 116 mu W at an acceleration of 1 g and a resonant frequency of 203 Hz. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.