(510c) Directed Assembly of Binary Anisotropic Magnetic Particles

The assembly of magnetic particles has recently gained attention for applications such as targeted drug delivery, photonic devices, and microrobots. The point dipole model has been used to quantify the interactions between magnetized particles, but different studies suggest that this model is not valid for anisotropic shapes. Our approach implements the ellipsoidal dipole model on Monte Carlo simulations to analyze the assembly of binary systems composed of ellipsoids of different shapes and material properties. The input variables for the model include field strength, medium properties, and the concentration ratio of the individual components. We validate the simulation results with past experiments on binary systems with the same variables. We investigate the effect of the dipolar interactions on the order and symmetry of binary structures composed of ellipsoidal particles of different shapes and material properties.

Simulation results show that the equilibrium structures are tunable based on the particle shapes and sizes, and particle and medium magnetic permeabilities. The simulated equilibrium structures change in their relative orders between paramagnetic and diamagnetic ellipsoids but keep the same fold symmetry at different medium permeabilities. Furthermore, varying the relative aspect ratio of the particles results in tunable structures that change from four-fold to five-fold symmetry. The simulation results show that the order and symmetry of equilibrium assembled structures can be controlled by varying the magnetic properties of the medium and the magnetic field intensity, establishing design tools for microrobots and tunable materials.