The number of ways to harvest energy that would otherwise go unused and wasted is extraordinary. To cite a few of the many examples, there’s the heat given off during almost any physical or electronic process, ambient light which is “just there,” noise, and ever-present vibration. Each of these has different attributes along with pros and cons which are fluid with respect to consistency, reliability, and, of course, useful output power in a given situation.
For example, the harvesting of vibration-sourced energy is attractive (when available) as it is unaffected by weather or terrain conditions. However, most of the many manifestations of such energy are quite small. It requires attention to details and design to extract and squeeze out a useful amount in the energy chain from a raw source to the harvesting transducer.
Most vibrations in daily life are tiny and often not “focused” but spread across a wide area or volume. To overcome this significant issue, numerous conversion devices, typically piezoelectric elements, are often installed in multiple locations that are exposed to relatively large vibrations.
Addressing this issue, a research effort lead by a team at KRISS—the Korea Research Institute of Standards and Science in the Republic of Korea (South Korea) —has developed a metamaterial that traps and amplifies micro-vibrations into small areas. The behavior of the metamaterials enhances and localizes the mechanical-energy density level at a local spot in which a harvester is installed.
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