Imec Presents MEMS Energy Harvester

Imec and Holst Centre announced they have made a micromachined harvester for vibration energy with a record output power of 489µW. Measurements and simulation show that the harvester 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 .

Imec’s innovative 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.