Piezoelectric MEMS boosts vibration harvester

April 28, 2011 // By R. Colin Johnson
Electrical engineers from the University of Michigan claim to have invented a technique for micro-machining piezoelectric MEMS that generate 10-times more energy than conventional energy harvesters. The research team said a penny-sized piezoelectric MEMS could generate enough electricity to power medical implants in the body and wireless sensors on motor vehicles.

The energy harvester market for wireless sensor networks is expected to $450 million by 2015, according to Erkan Aktakka, one of the system's developers, working in the lab of professor Erkan Aktakka, principle scientist on the project.

The team packaged its bulk micro-machined MEMS together with tiny circuit elements that form a complete vibration energy harvester in just 27 cubic millimeters. The tiny unit can harvest vibrational energy between 14-and-155 cycles-per-second (Hz) to produce about 200 microWatts from 1.5g vibrations. The energy harvester charges a supercapacitor to 1.85 volts, whereupon it powers-up the wireless sensor whose battery is it replacing. The researchers estimate the energy harvester could repeat this cycle for 10-to-20 years without degradation.

Details of the design will be revealed by the researchers in a presentation at Transducers 2011 (June 5-9, Beijing).

Funding was provided by the Defense Advanced Research Projects Agency and National Nanotechnology Infrastructure Network.

Self-contained energy harvester converts vibrations into electricity using bulk micromachined piezoelectrics.