Many-body electrohydrodynamic contact dynamics in alternating-current dielectrophoresis: Resolving hierarchical assembly of soft binary colloids

This study establishes a transient numerical framework integrating many-body electrohydrodynamic contact dynamics to predict hybrid crystal architectures in deformable binary colloids [5 μm SiC (P-type)/latex particles (N-type)] under 1 MHz alternating-current dielectrophoresis. By combining sharp-interface modeling with gap-dependent contact algorithms (250 nm offset), the framework resolves electromechanical interactions in systems with >20 particles, exceeding prior rigid-body limits (≤6 particles). Key advances include (1) penalty-based repulsive potentials enabling sub micrometer gap resolution (0.05× particle radius); (2) real-time tracking of hierarchical assembly from dipolar chains to 2D superlattices under 105 V m−1 fields; and (3) identification of compliance-driven pathways (e.g., lateral attractions forming diamond clusters at 108 Pa Young's modulus). Simulations reveal that surface-averaged electric energy density increases monotonically to plateaus, with P-only assemblies consistently attaining higher final energy densities than binary dimers, while percentage strain fields (10−6%–1%) validate modulus-dependent deformation. This framework provides pre-experimental guidance for field-programmable colloidal meta-materials, bypassing trial-and-error in microfluidic dielectrophoretic assembly.