Researchers at the University of Gothenburg have made light-powered gears on a micrometer scale. This paves the way for the smallest on-chip motors in history, which can fit inside a strand of hair.

This article was updated March 6, 2023. It was originally published Aug. 1, 2001. Gears—even plastic ones—need to be lubricated if engineers are going to coax the best performance out of them. In the ...