Laser pulse-droplet interaction enables the deformation and fragmentation of droplet array

TL;DR

This paper demonstrates how laser pulses can precisely control the deformation and fragmentation of droplet arrays, revealing new breakup mechanisms and enabling applications in industry and medicine.

Contribution

It introduces a novel experimental approach to manipulate droplet interactions using laser-induced optical breakdown, revealing a new butterfly-type breakup mechanism.

Findings

Controlled droplet deformation and fragmentation achieved

Discovery of butterfly-type breakup mechanism

Laser parameters influence droplet dynamics and fragmentation

Abstract

Droplet-droplet interactions is ubiquitous in various applications ranging from medical diagnostics to enhancing and optimizing liquid jet propulsion. We employ an experimental technique where the laser pulse interacts with a micron-sized droplet and causes optical breakdown. The synergy of a nanosecond laser pulse and an isolated spherical droplet is accurately controlled and manipulated to influence the deformation and fragmentation of an array of droplets. We elucidate how the fluid dynamic response (such as drop-drop and shock-drop interactions) of an arrangement of droplets can be regulated and optimally shaped by laser pulse energy and its interplay with the optical density of liquid target. A new butterfly type breakup is revealed, which is found to result in controlled and efficient fragmentation of the outer droplets in an array. The spatio-temporal characteristics of a laser-induced breakdown dictate how shock wave and central droplet fragments can influence outer droplets. The incident laser energy and pulse width employed in this work are representative of diverse industrial applications such as surface cleaning, nano-lithography, microelectronics, and medical procedures such as intraocular microsurgery.