A wildlife biologist contacted me to ask how he could extend the battery life of animals he was tracking. I told him there are tracking collars that can sleep 90 percent of the time using a micro-amp of current while storing sunlight energy during the day. These devices might only need to wake up to get some data for a second and transmit it to a Zigbee or wi-fi device or a satellite -- then go back to sleep.
Design News and Digi-Key sponsored a class by Paul Nickelsberg April 15 - 19, 2013 on energy harvesting. I was amazed that in lectures four and five, he introduced devices that could harvest energy that produced only millivolts of output (vibrations, for example, and signals from the "air"). What's cool is that these signals from microwave radiation would have been just wasted. In fact, they might have contributed to reflected confusion in other networks, so harvesting these might do others a favor. Well, not really. There is so much radiation out there.
I encourage others interested in this subject of harvesting micro amounts of energy to take the archived class.
He said he thinks the technology could open up more applications than you could ever dream of. I second that notion. This is very futuristic. Considering how much stray RF there is floating in the air, right in front of your eyes, at this very instant; I always thought it was a fascinating fact that turning on a transistor radio right in your hand could catch the signal of anything transmitting within 50 miles. Think of how much energy that actually is, available for this harvesting concept!
I agree. This technology could really help with in-the-field devices that are placed in places where batteries are hard to change. This also sounds like the ambient power sources is easier to harvest than ambient vibrations. Not all device placements are near freeways and bridges.
"Researchers at the University of Washington (UW) have developed wireless devices that are powered and communicate solely by harvesting signals from existing television and cellular transmissions in the air."
Elizabath, that's great and I think self powered board is a good model. I would like to whether anywhere (cell/battery) the energy is stored in wireless device or it's like a real time sourcing from air.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.