And it’s smaller than a penny.
The team was based at the University of Michigan under Khalil Najafi, the chair of the electrical and computer engineering at the university in Ann Arbor.
Najafi said, “In a tiny amount of space, we’ve been able to make a device that generates more power for a given input than anything else out there on the market.”
The “vibration energy harvester” is specifically designed to turn the cyclic motions of factory machines into energy to power wireless sensor networks. These sensor networks monitor the machines’ performance and let operators know about any malfunctions.
The sensors that do this today get their power from a plug or a battery. They’re considered “wireless” because they can transmit information without wires. But being tethered to a power source drastically increases their installation and maintenance costs, said Erkan Aktakka, one of the system’s developers and a doctoral student at Michigan from Turkey.
“If one were to look at the ongoing life-cycle expenses of operating a wireless sensor, up to 80 percent of the total cost consists solely of installing and maintaining power wires and continuously monitoring, testing, and replacing finite-life batteries,” Aktakka said. “Scavenging the energy already present in the environment is an effective solution.”
Najafi said, “There are lots of energy sources surrounding us. Lightning has a lot of electricity and power, but it’s not useful. To be able to use the energy you harvest, you have to store it in a capacitor or battery. We’ve developed an integrated system with an ultra capacitor that does not need to start out charged.”
The active part of the harvester that enables the energy conversion occupies just 27 cubic millimeters. The packaged system can sit comfortably on a penny.
In theory, these devices could be left in place for 10 to 20 years without regular maintenance. “They have a limitless shelf time, since they do not require a pre-charged battery or an external power source,” Aktakka said.
He estimated the market for power sources for wireless sensor networks in industrial settings would reach $450 million by 2015.
Najafi said the new devices could have applications in medicine and the auto industry as well. They could possibly be used to power medical implants in people or heat sensors on vehicle motors, he said.
Najafi, who came to the United States in 197?, has spent most of his adult life at the University of Michigan. He received his BS, MS and Ph.D., all in electrical engineering, from the university in 1980, 1981 and 1986 and has taught there ever since. Najafi holds 20 US patents.
