Selective Trapping andManipulation of MicroscaleObjects Using Mobile Microvortices.

Controlled manipulation of individual micro- and nanoscaleobjectsrequires the use of trapping forces that can be focused and translatedwith high spatial and time resolution. We report a new strategy thatuses the flow of mobile microvortices to trap and manipulate singleobjects in fluid with essentially no restrictions on their materialproperties. Fluidic trapping forces are generated toward the centerof microvortices formed by magnetic microactuators, that is, rotatingnanowire or self-assembled microbeads, actuated by a weak rotatingmagnetic field (|B|< 5 mT). We demonstrate precisemanipulation of single microspheres and microorganisms near a solidsurface in water. [ABSTRACT FROM AUTHOR]