Harvesting the vast energy potential of low-frequency vibrations for the powering of small-scale electronic devices has long been a goal of researchers in the field of microelectronics, and one that is looking increasingly likely to be achieved, based on recent developments.
Researchers at the Agency for Science, Technology and Research’s (A*STAR) Institute of Microelectronics have created an energy harvester that can harvest the energy of vibrations across a relatively wide frequency range, and in a number of different types of environments — qualities that place the new design on an entirely different level than previous ones.
Image Credit: Vibrations via Flickr CC
Earlier designs have generally been much more limited in their harvesting range, often only operating at one fixed frequency. Previous work has also relied on the expansion of device size in order to increase maximum power output — which limits the potential applications of the device. In order to address these issues, the researchers have started from scratch.
A*STAR provides details:
To address these design challenges, IME researchers have demonstrated an aluminium nitride (AlN) based energy harvester with record-high power density of 1.5 x 10-3 W/cm3 capable of generating electricity equivalent to three commercial implantable batteries over a 10-year period. As an inexorable power supply, the remarkable power density feature translates into massive savings as costs and logistics associated with power source servicing will no longer be relevant.
The energy harvester also extends the flexibility of low frequency vibrational sources that can be harvested by offering the widest sampling range of 10th — 100 Hz. The wide sampling range makes it now possible to more productively harness real-world vibrational sources in spite of their irregularity and randomness.
Researcher Dr Alex Gu, Technical Director of IME’s Sensors and Actuators Microsystems Programme, explained: “Our design strategy exploits the coupling effect between the Vortex shedding and Helmholtz resonating in order to enhance the Helmholtz resonating and lower the threshold input pressure. By transferring the low frequency input vibrational energy into a pressurised fluid, the fluid synchronizes the random input vibrations into pre-defined resonance frequencies, thus enabling the full utilization of vibrations from the complete low frequency spectrum.”
Professor Dim-Lee Kwong, Executive Director of IME, added: “This breakthrough presents tremendous opportunities to realise a practical, sustainable and efficient energy renewal model with attractive small-form factor, low cost solution for a wide range of applications from implantable medical devices, wireless communication and sensor networks, to other mobile electronics that enable future mobile society.”
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