Manipulation of a Micro-Object Using Topological Hydrodynamic Tweezers

At the microscale, noncontact control of objects plays a key role in physics, chemistry, biology, and information science, but is susceptible to external disturbance. This study demonstrates a method based on an innovative trapping mechanism to manipulate a micro-object controllably, using a toroidal vortex at ambient conditions. By taking advantage of the nonlocal topological property of the vortex flow field, the object is intrinsically protected from external disturbance. This manipulation technique will be useful in scenarios such as scanning-image short-range weak-interaction sensing, as well as a broad range of applications involving rotational degrees of freedom.