Antibubbles: evidences of a critical pressure

TL;DR

This paper investigates antibubbles, revealing a critical pressure at which they become unstable, and introduces a modified Laplace law to explain their stability and the relationship between shell thickness and pressure.

Contribution

It provides the first experimental analysis of antibubbles' stability and introduces a modified Laplace law accounting for surfactant interactions to explain critical depth.

Findings

Antibubbles sink and pop at a specific depth due to critical pressure.

A modified Laplace law describes the air shell thickness evolution.

Critical pressure determines antibubble stability.

Abstract

We present experimental investigations of antibubbles. Such an unusual fluid object is a thin spherical air shell surrounding a liquid globule. We explain how to produce them and we study their stability. By overweighting antibubbles with a small amount of salt, they sink and pop at a definite depth. A critical depth related to a critical pressure has been found. A modified Laplace law describes the air shell thickness evolution with respect to pressure. This law combined with surfactant layers interaction allows to explain the critical depth for antibubble stability.