Microfluidic sorting of stereoisomers.

Isomeric molecules that only differ in the spatial orientation of their constituents are called stereoisomers. We demonstrate that different stereoisomers are transported typically at different velocities in a fluid streaming through a straight microchannel. As the underlying mechanism, we identify a translation-rotation coupling in the motion of the molecules which is specific for the molecule structure. This effect can be exploited for the separation of stereoisomers, a task of immense importance in biotechnology and pharmaceutics.