Capturing ambient electromagnetic energy to drive small electronic devices

July 8, 2011
Sensor Antenna

Georgia Tech School of Electrical and Computer Engineering professor Manos Tentzeris holds a sensor (left) and an ultra-broadband spiral antenna for wearable energy-scavenging applications. Both were printed on paper using inkjet technology (credit: Georgia Tech Photo/Gary Meek)

Researchers at Georgia Tech School of Electrical and Computer Engineering have discovered a way to capture and harness energy transmitted by radio and television transmitters, cell phone networks, and satellite communications systems by scavenging ambient energy from the air.

The researchers used inkjet printers to print sensors and ultra-wideband antennas on paper or flexible polymers, functioning from 100 MHz to 60 GHz.

The resulting self-powered wireless sensors could be used for radio-frequency identification (RFID) tagging for manufacturing and shipping, and monitoring communications and power usage, and chemical, biological, heat and stress sensing for defense and industry, the researchers said.

Other applications include airport security (detecting potential threats such as explosives or smuggled nuclear material), monitoring home temperature and humidity, detecting chemicals that indicate food spoilage, and self-powered sensors on buildings, bridges or aircraft that could watch for problems.

Scavenging experiments utilizing TV bands have already yielded power amounting to hundreds of microwatts, and multi-band systems are expected to generate one milliwatt or more. The researchers said that amount of power is enough to operate many small electronic devices, including a variety of sensors and microprocessors.

By combining energy-scavenging technology with supercapacitors and cycled operation, the researchers expect to power devices requiring more than 50 milliwatts. Using this approach, energy builds up in a battery-like supercapacitor and is utilized when the required power capqacity is reached.

A presentation on this energy-scavenging technology was given July 6 at the IEEE Antennas and Propagation Symposium in Spokane.