A microfluidic system, based on the use of microcabities, which are tiny re-circulating flows that controllably generate in microchannels, was analyzed. The system illustrated the intriguing possibilities when unique micro-fluidic behaviors were applied towards biological and cellular manipulatios. Re-circulating flows or vortices are formed when flow detachment occurs, and can be generated under a wide range of conditions. Microvortices formed in secondary chambers, where the re-circulation is driven by another microvortex, often provide the stable conditions required for single-cell rotation. Microvortices also helps in exerting rotational control over single cells. They can also be applied towards the manipulation of subcellular structures, such as single DNA molecules. Results shows that an advantage of using microvortex to rotate objects is the great dynamic range and the precision with which single cells and microparticles can be rotated.