As wireless sensor nodes become smaller, their energy supply is a limiting factor for further miniaturization as integration density is limited by the space requirements of the energy storage system. MEMS based energy harvesters, such as the one shown in this example, are becoming a key enabler for further miniaturization and deployment of energy autonomous sensor nodes.
Vibration harvesting taps into energy present in moving structures. Several physical effects can be employed to transform mechanical to electrical energy. Piezoelectric, electrostatic or electrodynamic effects are the most common approaches. In this example we show a piezoelectric vibrational energy harvester, similar to the devices shown in Figure 1, fabricated from silicon by a combination of wet and dry etching techniques. This device is designed to be integrated into a energy harvesting module together with a power transfer circuit, a storage element and a resistive load.