Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe.

Juan V Escobar,Rolando Castillo,Cristina Garza

doi:10.3762/bjnano.8.84

Abstract

We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process between a liquid drop and rough surfaces using a conventional atomic force microscope. In this method, a micrometric liquid mercury drop is attached to an AFM tipless cantilever to measure the force required to pull this drop off a rough surface. We test the method with two surfaces: a square array of nanometer-sized peaks commonly used for the determination of AFM tip sharpness and a multi-scaled rough diamond surface containing sub-micrometer protrusions. Measurements are carried out in a nitrogen atmosphere to avoid water capillary interactions. We obtain information about the average force of adhesion between a single peak or protrusion and the liquid drop. This procedure could provide useful microscopic information to improve our understanding of wetting phenomena on rough surfaces.

Highlights

After the introduction of the atomic force microscope (AFM), it was clear that force-vs-distance curves could be measured using this new instrument and that several fields related to adhesion [1] could be promoted in new directions
We present a procedure to measure the force of adhesion between a liquid drop and rough surfaces, in which a micrometric liquid drop replaces the colloidal particle on a tipless cantilever
A method was developed to perform and interpret pull-off force measurements during the jump-off-contact process between a micrometric liquid drop attached to an AFM tipless cantilever and rough surfaces

Summary

Introduction

After the introduction of the atomic force microscope (AFM), it was clear that force-vs-distance curves could be measured using this new instrument and that several fields related to adhesion [1] could be promoted in new directions. We present our results as well as a discussion of the measured force of adhesion between three pairs of contacting bodies: a) An array of sharp silicon peaks and a mercury drop probe.

Results

Conclusion