This paper presents a homogeneity analysis of a high yield wafer scale fabrication of MEMS-based unimorph silicon/PZT thick film vibration energy harvesters aimed towards vibration sources with peak vibrations in the range of around 300Hz. A wafer with a yield of 91% (41/45 devices) has been characterized. Measurements of the open circuit voltage showed a relative difference of 32.6% between the standard deviation and average. Measurements of the capacitance and resonant frequency showed a relative difference between the standard deviation and average value of 4.3% and 2.9% respectively, thus indicating that the main variation in open circuit voltage performance is caused by varying quality factor. The average resonant frequency was measured to 333Hz with a standard variation of 9.8Hz and a harvesting bandwidth of 5-10Hz. A maximum power output of 39.3μW was achieved at 1g for the best performing harvester.
Procedia Engineering, 2012, Vol 47, p. 554-557
Energy harvesting; Vibration harvesting; MEMS; PZT; Thick film