Active Magnetically Assembled Colloidal Chains: From Fundamentals to Applications

Magnetic particles have revolutionized biological separations and are an integral part of many bead-based characterization assays. Also, due to their assembly properties, suspensions containing such particles can be utilized as smart fluids with magnetic-field-dependent viscosities. Here, we will add another degree of freedom to this system, namely, time varying magnetic fields, and explore the emergent dynamics of such particles and chains in different conditions. Of particular interest is the assembly and disassembly of these chains as a function of the frequency of rotation of the magnetic field. Also, near surfaces these particles/chains display non-trivial couplings between the rotational and translational degrees of freedom. The findings from these fundamental studies can be used to measure surface-surface interactions in a simple, yet sensitive and precise way. Biological examples of such systems will be presented.