Numerical studies on micropart self-alignment using surface tension forces

Abstract

The Fluidic Self-Alignment Approach provides an alternative means for fast, economic, and precise handling of thousands of micro-scale parts. The present study aims to examine the important parameters which govern the mechanisms of the fluidic self-assembly process by numerical simulations. A simplified 2D model system consists of a solid plate, a micro-scale liquid slug and a micropart. The computational model is based on first principle conservation equations and is constructed by the coupling of two-phase modeling, solid structure modeling, and fluid–structure coupling. A matching experimental system is set up for the micropart of aspect ratio from 3:1 to 10:1 to validate the 2D computational simulations. Simulations reveal that a high degree of hydrophilicity between the lubricant and the solid surfaces is required for the self-assembly of microparts. A lower lubricant height, a higher surface tension coefficient and a higher viscosity enforce the re-alignment/restoration process also. Characterization of the flow field inside lubricant slug also indicates that the asymmetry of the vortices/stress distribution at both ends of the lubricant meniscus is resulted as the micropart in a back-and-forth restoration process.