An inch-long array of some of the tiniest solar cells ever built has been successfully tested as a power source for microscopic machines, a new study reports. Instead of using silicon, Xiaomei Jiang and her colleagues from the University of South Florida turned to a polymer (a long organic molecule made of repeating structural units). The polymer they selected has the same electrical properties as silicon wafers, but can be dissolved and printed onto flexible material. Jiang and her colleagues made 20 tiny cells - each the size of a lower case "o" in standard 12-point print - and joined them together in an array to power a microscopic chemical detector. Read more here.