Energy Harvesting Radios

What if the perpetual power source and radio were combined in one small package?

Sensors using radio transmitters to relay data back to a data collection point are not new, nor is the idea of using solar power to operate these transmitters.

Solar powered instruments dot the volcanoes on the island of Hawaii and you may have seen monitoring stations near streams, reservoirs or along the road powered by solar cells.

What if the perpetual power source and radio were combined in one small package?

That's the goal of engineers at Kansas State University. They have demonstrated a prototype of an “energy-harvesting radio” that includes the solar cells with the radio. The energy-harvesting radio is being developed for Peregrine Semiconductor, an integrated circuit manufacturer in San Diego.

Bill Kuhn. Kansas State professor of electrical and computer engineering, and Xiaohu Zhang, master's student in electrical engineering, are working on the project.

“This type of radio technology may exist in your house, for instance if you have a temperature sensor outside that radios data to a display inside,” Kuhn said. “But those devices need to have their batteries changed. This radio doesn't."

Potential applications include monitoring stress, temperature and pressure on bridges and other structures. Peregrine provides the low power radio chips, using its trademarked UltraCMOS silicon-on-sapphire technology, required to work with the diminutive power sources. Power is not limited to solar cells. Kuhn said the energy-harvesting radios could be powered by electrochemical, mechanical or thermal energy as well. Capacitors are used to store the energy instead of a battery.

Kuhn and Zhang are working to perfect the radio system design by determining which frequencies to use and looking at how noise and other factors may limit the sensitivity of the receiver picking up the data from all of the sensors.

Their research will be presented at the Radio and Wireless Symposium in January 2009.

Read more of Doug Lung's RF Reporthere.