A vibration energy harvester using AlN piezoelectric cantilever array

• A piezoelectric vibration energy harvester using AlN cantilever array is presented.
• The AlN cantilever beam array is fabricated using MEMS technology.
• The output power of the harvester is increased by connecting the array in series.
• For series connection, the power loss in rectification circuit is reduced largely.

A micro-piezoelectric cantilever array device for vibration energy harvesting was designed, microfabricated and characterized. This device consists of five piezoelectric cantilever beams and a single proof mass. Aluminum/aluminum nitride/molybdenum (Al/AlN/Mo) multilayer films were deposited and patterned on a silicon wafer using the magnetron sputtering method and corresponding etching methods. Then the piezoelectric cantilever array and proof mass were patterned and released using deep-reactive ion etching. The open circuit voltages and output power of the five piezoelectric cantilevers were measured at different acceleration (0.2 to 1.0 g). The array were connected in series and parallel and the maximum generated powers are 0.935 and 3.315 μW under 1.0 g, respectively. Then a full wave rectifier was used to convert the alternative current into direct current. The output powers of the array in series and parallel connection reduce to 0.342 and 0.276 μW under 1.0 g, respectively. The power loss in the rectifier for parallel case is 5 times that for series case, which demonstrates that series connection for array harvester can effectively decrease the power loss in the rectifier.

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