In a spin
(a) Schematic of single cell detection using a magnetic microsphere: The magnetic microsphere is coated with special antibodies that grab hold of the bacterium. (b) Series of successive fluorescence microscopy images of a rotating 2 micron-sized magnetic microsphere with an attached E. Coli bacterium. The dotted circles indicate the location of the magnetic microsphere, where the axis of rotation lies in the plane of the sample. (Courtesy: Applied Physics Letters).