Vibrational energy harvesting power supply features highest efficiency

The prototype is comprised of a Holst Centre/imec power management IC and an OMRON electret energy harvester. It can convert and store energy from µW vibrations with high efficiency to the driving voltage of general sensors. It measures 5x6cm (with the potential to shrink as small as 2x2cm) and weighs just 15.4g. Combined with the user-variable output voltage range of 1.5-5V, this makes it suited for various autonomous wireless sensor node applications in the industrial and consumer domains, particularly those applications in inaccessible locations.

Researchers from Holst Centre/imec, working with OMRON, integrated the electrostatic harvester and power management electronics into a power-optimised module. The variable output voltage provides increased flexibility to replace any kind of battery in existing designs or create new ones. The module contains an ON/OFF signal for efficient duty cycling with low power sensor systems.

René Elfrink, Senior Researcher, Sensors & Energy Harvesters, Holst Centre/imec, commented: “Energy harvesting - extracting unused or waste energy from the local environment - is perfect for autonomous sensor nodes. It does away with the need for cables and changing batteries, allowing true 'fix-and-forget' systems. 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."

OMRON is currently putting the prototype through a number of field tests with customers to gain further input before entering volume production.

“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 has equipment control and predictive maintenance systems,” adds Daido Uchida, General Manager, Technology Produce & Start-up division, OMRON.