Non-Contact manipulation of microbeads via pushing and pulling using magnetically controlled clusters of paramagnetic microparticles

In contact micromanipulation, the adhesive forces between manipulators and microobjects decrease the chances of achieving successful releases at the desired positions. We study a non-contact micromanipulation technique of microbeads (300 μm in average diameter) using clusters of paramagnetic microparticles (100 μm in average diameter). This non-contact micromanipulation is done using the hydrodynamic forces instead of the interaction forces in contact manipulation, and hence eliminates the adhesive forces that decrease the chances of achieving successful releases. Motion of the cluster of microparticles results in a pressure gradient (within the vicinity of the microbead in a fluid) that derives and steers the microbeads without contact. The microparticles are moved under the influence of controlled magnetic field gradient to push or pull the microbeads towards reference positions. We achieve non-contact manipulation via pushing and pulling at average speeds of 219 μm/s and 258 μm/s for the microbead, respectively (using cluster of 10 microparticles). The noncontact pushing and pulling localize the microbeads within the vicinity of reference positions with average steady-state errors of 177 μm and 100 μm, respectively. Moreover, we experimentally demonstrate non-contact microassembly of 3 microbeads into an L-shape at a task completion time of 25 seconds.