Magnetically-Programmable Cylindrical Microparticles by Facile Reaping Method

Various shapes of magnetically-programmed polyethylene glycol (PEG)-based particles with Fe₃O₄ blocks were harvested by a facile reaping method. Specifically, elastic PEG-based particles can be obtained by applying uniform shear stress onto the array of densely-populated PEG/Fe₃O₄ microstructures. A simple theory based on geometric and material properties was developed based on experimental observations to produce highly uniform cylindrical microparticles in a cost-effective manner. We analyzed the force balance of hairy architectures to explain the uniform cutting process, which is based on operating zones with various geometries and material elasticity. Here, the alignments of mono-/multi-dispersed iron oxide (Fe₃O₄) in microparticles can be tunable by changing the external magnetic field during replications. Furthermore, the collective reversible motions of different magneto-responsive PEG particles were observed when the external magnetic field was controlled, wherein such behaviors can be applied in potential medial applications such as controllable drug-delivery or microrobotics. [Figure not available: see fulltext.].