Incredibly tiny windmills may be the next significant innovation in clean energy.
Research associate Smitha Rao and electrical engineering Professor J.-C. Chiao have designed and built a micro-windmill that can harvest wind energy to power batteries. Each device is about 1.8 mm at its widest point, so a single grain of rice could hold about 10. To charge a cellphone, thousands of the windmills would be embedded within the device’s packaging to collect energy from the airflow in the environment.
“Imagine that in the future you could put a sleeve on your smartphone, wave it in the air for a while, and then use it again,” says Dr. Chiao, who holds the Janet and Mike Greene and the Jenkins Garrett professorships in electrical engineering.
The idea for the micro-windmills came when Taiwan-based WinMEMS Technologies asked Chiao and Dr. Rao for novel device designs and applications for the company’s fabrication techniques, which are known in the semiconductor industry for their reliability.
“Imagine that in the future you could put a sleeve on your smartphone, wave it in the air for a while, and then use it again.”
The invention has gained widespread national and international exposure, with coverage by The Washington Post, Time, Wired, National Geographic, FOX Business News, and many foreign media outlets. Online videos of the windmill tallied almost a quarter-million views in three weeks.
The researchers tested the devices in September in Chiao’s lab. They can operate under strong artificial winds without fracturing because they’re made from durable nickel alloy and have a simple yet smart aerodynamic design.
“The problem that often arises when designing these types of miniature robotic systems is that the materials are too brittle,” Rao explains. “With the alloy, we don’t have that same issue. ”
Additionally, the micro-windmills can be produced in an array using batch processes, making them relatively inexpensive. The cost of fabricating one device is the same as making hundreds or thousands on a single wafer.
Because of their small size, thousands of windmills could potentially be embedded into flat panels and mounted on the walls of buildings, bridges, or highways to harvest energy for lighting, security or environmental sensing, and wireless communication.
“It’s very gratifying to work on something like this where you can see immediately how it might be used,” Rao says. “But I think we’ve only scratched the surface of the micro-windmills’ potential applications.”