Acoustically propelled nano- and microcones: fast forward and backward motion

TL;DR

This study uses computer simulations to analyze how the aspect ratio of cone-shaped nano- and microparticles affects their ultrasound-driven propulsion, revealing that shape influences both speed and direction, with implications for particle sorting.

Contribution

It provides new insights into the relationship between particle shape and propulsion direction and speed, guiding future experimental design and applications.

Findings

Propulsion velocity and direction are highly sensitive to aspect ratio.

Short particles move forward, elongated particles move backward.

Identified cone shape for maximum propulsion speed.

Abstract

We focus on cone-shaped nano- and microparticles, which have recently been found to show particularly strong propulsion when they are exposed to a traveling ultrasound wave, and study based on direct acoustofluidic computer simulations how their propulsion depends on the cones' aspect ratio. The simulations reveal that the propulsion velocity and even its sign are very sensitive to the aspect ratio, where short particles move forward whereas elongated particles move backward. Furthermore, we identify a cone shape that allows for a particularly large propulsion speed. Our results contribute to the understanding of the propulsion of ultrasound-propelled colloidal particles, suggest a method for separation and sorting of nano- and microcones concerning their aspect ratio, and provide useful guidance for future experiments and applications.