Low-Bond Axisymmetric Drop Shape Analysis for Surface Tension and Contact Angle Measurements of Sessile Drops
A.F. Stalder, T. Melchior, M. Müller, D. Sage, T. Blu, M. Unser
Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 364, no. 1-3, pp. 72–81, July 20, 2010.
A new method based on the Young-Laplace equation for measuring contact angles and surface tensions is presented. In this approach, a first-order perturbation technique helps to analytically solve the Young-Laplace equation according to photographic images of axisymmetric sessile drops. When appropriate, the calculated drop contour is extended by mirror symmetry so that reflection of the drop into substrate allows the detection of position of the contact points. To keep a wide range of applicability, a discretisation of the drop's profile is not realised; instead, an optimisation of an advanced image-energy term fits an approximation of the Young-Laplace equation to drop boundaries. In addition, cubic B-spline interpolation is applied to the image of the drop to reach subpixel resolution. To demonstrate the method's accuracy, simulated drops as well as images of liquid coal ash slags were analysed. Thanks to the high-quality image interpolation model and the image-energy term, the experiments demonstrated robust measurements over a wide variety of image types and qualities. The method was implemented in Java and is freely available.
The associated software is available here.
@ARTICLE(http://bigwww.epfl.ch/publications/stalder1001.html,
AUTHOR="Stalder, A.F. and Melchior, T. and M{\"{u}}ller, M. and Sage, D.
and Blu, T. and Unser, M.",
TITLE="Low-Bond Axisymmetric Drop Shape Analysis for Surface Tension and
Contact Angle Measurements of Sessile Drops",
JOURNAL="Colloids and Surfaces {A}: {P}hysicochemical and Engineering
Aspects",
YEAR="2010",
volume="364",
number="1-3",
pages="72--81",
month="July 20,",
note="")