Active control of dynamic supraparticle structures in microchannels

Paramagnetic particles in microchannels form dynamic and reversible self-as sembled regularly spaced structures when exposed to an external magnetic fi eld. The magnetically induced micron-scale patterns can be formed and refor med spontaneously, thus providing an alternative to traditional microfabric ation techniques for pattern creation. Under the influence of a varying mag netic field, these structures could be rotated through all axes without los s of structural form allowing dynamic micron-scale movement; without direct mechanical, electrical, or photonic interactions. The structures are not a ttached to the wall of the enclosure and are free to move without loss of f orm from both pressure-induced flow and electrokinetic effects. The dynamic supraparticle patterning can be used in an extensive variety of on-chip ap plications and for unique microfabrication techniques.