The key to such perpetual devices is that they perform these tasks indefinitely, thereby eliminating the need to replace batteries. Energy harvesting is increasingly becoming a hot topic. But "what has really changed energy harvesting in the last two decades?" asked Patrick Mannion, editorial director of TechOnline, who moderated the energy harvesting panel at Embedded Systems Conference on Tuesday (March 31).

The answer, in sum, is a confluence of the development of wireless and lower power electronics, along with advancements in sensors and MEMS. The result is a combination of factors that is fundamentally changing today's energy-harvesting market.

The development of low-power electronics and wireless technologies made it "viable" to use harvested energy for a number of applications, said Dave Freeman, engineering manager at Texas Instruments.

Patrick Chapman, associate professor at University of Illinois, agreed. "The power of wireless communication devices has become so low that we can finally start doing something about small, harvested energy," he said.

Eugene You, application engineering manager at EnOcean, added, "Don't forget the price of wireless devices." With a steady decrease in the cost of wireless devices, he said, "We can now put [perpetual devices] everywhere for sending data wirelessly, and forget about it."

Nonetheless, you still need a power storage device, said Steve Grady, vice president of marketing at Cymbet Corp. Some systems are required to occasionally handle a large burst of energy. If you can store energy, such as in a thin-film battery Cymbet is developing, "you can respond to it faster," Grady added. And that energy storage device "needs to hold charge long-term."