Vibration harvester power supply claims highest-ever efficiency

July 23, 2014 // By Graham Prophet
An enabling technology for “fix-and-forget” sensor nodes, Omron and researchers Holst Centre/imec have jointly unveiled a prototype of an extremely compact vibrational energy harvesting DC power supply with worlds’ highest efficiency.

Combining Omron's electret energy harvester with a Holst Centre/imec power management IC, it can convert and store energy derived from vibrations in the µW range, with high efficiency, to deliver operating power at the driving voltage of general sensors. The prototype measures just 5 x 6 cm – with potential to shrink as small as 2 x 2 cm. Its small size, light weight (15.4 gram) and user-variable output voltage are ideal for a wide-range of autonomous wireless sensor node applications in the industrial and consumer domains, particularly in inaccessible locations.

Small, autonomous wireless sensors that can simply be installed and then left to collect and share data are attracting interest in the context of the Internet of Things, and to enable new levels of automation and equipment monitoring in industrial applications. However, a key question has been how to power them.

“The combination of Omron’s robust electrostatic vibration harvester and our efficient power management technology enables an extremely compact design that can be installed in even the most inaccessible places – whereas today’s vibrational harvester power supplies are too large and too heavy,” says René Elfrink, Senior Researcher Sensors & Energy Harvesters at Holst Centre/imec.

“The vibration in the environment of customers are various and volatile. Under such an environment, our harvester can produce energy, even just a little. But so far, we could not use our harvester as a stable DC power supply. Before developing this compact vibrational harvesting power supply, we benchmarked power management technologies from many potential partners and found Holst Centre/imec’s offering to be the most mature. The resulting power supply meets all the requirements for small, low-power wireless sensors, particularly industrial applications such as equipment control and predictive maintenance systems,” adds Daido Uchida, General manager of Technology Produce & Start-up division of Omron Corporation.

Working closely with Omron, researchers from Holst Centre/imec integrated the electrostatic harvester and power management electronics into a power-optimised module