THE NEXT BIG THING?

Getting Power From Airborne Energy Waves

A new device has been developed by Duke University researchers

Imagine motion sensors in a home-security system that power themselves from the energy waves permeating your home. Or earthquake sensors that could derive enough power to work from nearby cellular towers.

Duke University researchers have taken a step in that direction by using cheap parts to create a device that can capture energy waves wirelessly and turn them into power at roughly the same efficiency—37%—as solar panels achieve in converting sunlight. (click below to read more)

Invisible waves of electric and magnetic energy are ubiquitous in modern life, emitted by cellular networks, power lines, Wi-Fi devices and even household appliances. The challenge is to capture the waves in a cost-effective manner and then convert them into enough electricity to do some good.

That isn't easy, because the amount of power that can be wrung from the waves is low. The key in the Duke research is the use of "metamaterials" designed to excel at grabbing passing energy waves—copper wires, for example, optimally spaced to capture microwaves. These materials, whose elements are spaced closer together than the span of a wavelength, could someday be built into sensors and other low-power equipment, so that they can function without batteries or electricity from an outlet.

The Duke device, resembling a toy sailing ship with five 1.5-inch- square sails, also contains a rectifier to convert the microwaves into direct current. By firing microwaves at their device through a kind of funnel, the researchers produced 7.3 volts of electricity, nearly 50% more than is put out by a standard USB charger.

Real-world results would be much lower, but further research could produce enough power to serve the needs of some autonomous devices. The Duke scientists noted that their power-catcher could be customized to produce low levels of power from sound, satellite or Wi-Fi signals.