Experimental observation of sound-mediated stable configurations for polystyrene particles

TL;DR

This paper experimentally demonstrates how acoustically-induced forces cause polystyrene particles to self-organize into stable configurations, revealing two distinct types: mechanically balanced and close-packed assemblies, with results aligning with theoretical models.

Contribution

First experimental observation of sound-mediated stable configurations in polystyrene particles, validating theoretical predictions and modeling particle assembly behavior.

Findings

Two types of stable configurations observed: mechanical equilibrium and close-packed assemblies.

Inter-particle separations for small groups match theoretical predictions.

Number and probability of configurations increase with particle number, explained by a geometric model.

Abstract

Here we present an experimental observation of the self-organization effect of the polystyrene particles formed by acoustically-induced interaction forces. Two types of stable configurations are observed experimentally: one is mechanically equilibrium and featured by nonzero inter-particle separations, and the other corresponds to a close-packed assembly, which is formed by strong attractions among the aggregated particles. For the former case involving two or three particles, the most probable inter-particle separations (counted for numerous independent initial arrangements) agree well with the theoretical predictions. For the latter case, the number of the final stable configurations grows with the particle number, and the occurrence probability of each configuration is interpreted by a simple geometric model.