Effect of static electricity on IFT measurements by drop shape analysis

Abstract

Static charge, building up at the metallic needle of a drop shape analysis setup, can lead to inaccuracy and loss of repeatability in interfacial tension (IFT) measurements. In this short communication, we present a fast, straightforward and general modification to any IFT setup, experiencing this problem, which eliminates the effect of possible static charge. We were able to clearly demonstrate the effect of perturbation and the elimination thereof in simple experiments by touching the needle with large metallic objects. By grounding the needle, we were able to enhance accuracy and repeatability of the IFT measurements. This modification should inspire manufacturers of drop shape analysis devices to include a permanent ground for the metallic needle of dispensing systems.