‘Waste’ man-made electromagnetic energy is everywhere, coming from sources like power cables, radio transmitters and televisions. Harvesting that energy has long been regarded as impractical. However, two recent advances have changed that thinking: highly efficient collectors and devices that run on tiny electric currents.
Manos Tentzeris and Rushi Vyas, researchers at Georgia Tech in Atlanta, have invented wireless sensor devices that exploit ambient energy from transmission towers. The single unit incorporates energy-collecting antennae and the electronics that draw on it, printed onto paper or flexible polymer. The researchers use a special ‘ink’ that contains silver nanoparticles, which allows them to produce radio-frequency components, circuits and other sensing devices.
These inexpensive sensors have numerous potential uses, including remote chemical, biological, moisture and stress monitoring. For agriculture, the team has invented smart irrigation sensors powered by ambient energy. These constantly monitor soil moisture, and wirelessly instruct intelligent irrigation equipment precisely where and when to water. The system greatly reduces water and pumping costs, and the maintenance-free sensors and antennae degrade harmlessly into the soil at the end of their useful life.
The State of Georgia’s Centers of Innovation for Energy and Agribusiness are now working with the researchers to test and deploy the technology in real-life conditions. “We are very excited to assist with the implementation of this ground-breaking technology”, says Costas Simoglou, the Center’s Director.
The Georgia Tech team is also working with Assistant Professor Yoshihiro Kawahara of the University of Tokyo on a system of autonomous, maintenance-free, ambient energy-powered sensors for structural stress monitoring. These devices would flag strain changes in buildings and bridges that might indicate structural weakening, helping to avert catastrophic failure. As Kawahara adds, “This is particularly important in earthquake-prone Japan.”
‘Scavenger’ sensors could even hit the market sooner rather than later, according to Tentzeris. “Devices based on our technology should be commercially available within two years, and cost about a 10th of the price of those used today”, he claims.
Photo: Georgia Tech