FM-AFM with hanging fiber probe for the study of liquid / liquid interfaces

TL;DR

This paper introduces a novel frequency modulation AFM technique with a hanging fiber probe for precise, local measurements of liquid-liquid interfaces, enabling monitoring of interfacial phenomena over time.

Contribution

It presents the design, calibration, and application of a hanging fiber force probe in AFM for quantitative liquid-liquid interface studies, including interface deformation and tension measurements.

Findings

Successful measurement of water droplet evaporation at PDMS/water interface

Monitoring of interfacial tension evolution over hours

Observation of interface deformation during experiments

Abstract

This article describes how a frequency modulation AFM using a hanging fiber force probe made from a quartz tuning fork provides local measurements on liquid-liquid interfaces. After detailing the manufacture and calibration of the force probe, we provide evidence that this AFM is suitable for quantitative measurements at the interface between two liquids. The repeatability of the measurements allows a poly-dimethylsiloxane / water moving interface to be monitored over several hours : the evaporation of a water droplet immersed in poly-dimethylsiloxane is observed, and its interfacial tension evolution over time is measured. Deformation of the interface is also observed. These capabilities, and preliminary results on the interface between two immiscible liquids, pave the way for interface manipulation and study of complex fluid-fluid interfaces.