MEMS Energy Harvester Suitable for Shock-Induced Energy Harvesting

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A micromachined harvester for vibration energy boasts an output power of 489µW. Measurements and simulation show that the harvester developed by Imec is also suited for shock-induced energy harvesting in car tires, where it could power built-in sensors. In a tire, at 70km/h, the new device can deliver a constant 42µW, which is enough to power a simple wireless sensor node. These results, obtained within the research centre’s program for Micropower Generation and Storage, were presented at the 2011 IEEE International Electron Devices Meeting (IEDM) in Washington (Dec. 7-9). 

Imec’s harvester consists of a cantilever with a piezoelectric layer sandwiched between metallic electrodes, forming a capacitor. At the tip of the cantilever a mass is attached, which translates the macroscopic vibration into a vertical movement—putting strain on the piezoelectric layer and generating a voltage across the capacitor. As piezoelectric material, AlN (aluminum nitride) was chosen. The harvesters are packaged with a 6-inch wafer scale vacuum packaging process. The micromachining production process is compatible with low-cost mass-production fabrication.

Imec Leuven
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