The device is about 1.8 mm at its widest point and the windmills are so small, you would be able to fit ten of them on a single grain of rice.
The researchers say that hundreds of the windmills could be embedded in a sleeve for a phone.
Holding the phone up on a windy day or waving the phone around would generate the electricity needed to help charge its battery.
The metal alloy used to create the micro-windmill is flexible and durable and the researchers say they can withstand strong winds without fracturing.
Taiwanese tech company WinMEMS has struck a deal with the team to explore the opportunities for commercialisation.
Here's one of the windmills in action, although whether you will see them on a product remains to be seen.