We’ve been hearing about this imminent technology for a while, but today researcher Xiaomei Jiang said that spray-on solar cells have been successfully tested as a power source for microscopic machines. Jiang and her colleagues used flexible polymer as a base instead of silicon, which is brittle.

The researchers at the University of South Florida needed a power source for a microscopic sensor that can detect dangerous chemicals and toxins, which could potentially help locate chemical leaks. So they built an inch-long array of the tiniest solar cells ever built, and Jiang says this new technology could be used on practically any surface that’s exposed to sunlight, including straight onto rooftops and cars.

The cells Jiang and her colleagues created are each the size of a lower case “o” in standard 12-point print. The array provided 7.8 volts of power, about half of their goal, and Jiang says they expect to reach 15 volts by the end of the year.

Imagine the possibilities if this technology proves to be applicable for commercial and residential purposes. It’ll be interesting to see if it’s any more affordable than regular solar cells, and what its limitations are.