A web-based software for measuring the interfacial tension of a liquid and the contact angle of a droplet, by implementing Drop Shape Analysis (ADSA).


Based on the fitting of the Young-Laplace equation to a liquid droplet image data, DropUI calculates the contact angle of the droplet, as well as the surface tension of the liquid. The mathematical framework of the method as well as the validation against other, well-established, ADSA packages (ramé-hart DROPimage Advanced and ImageJ plugins DropAnalysis & Pendant_Drop) are described in reference [1].


Screenshot of the DropUI software calculating the contact angle of a sessile droplet.

Main Features

  • Automated liquid surface tracking by using a modified version of the threshold method.

  • Automated detection of droplet type (sessile or pendant).

  • Interfacial tension and Young's contact angle measurement by fitting a theoretical droplet profile (Young-Laplace equation) to the experimental image. The solution of the Young-Laplace equation can be performed either by numerical integration or with a computationally much more efficient method by using an artificial neural network.

  • DropUI is the successor of DropToolKit. No installation is now required. Just register and use the web-based interface.

Access the Software

DropUI is a web-based software which can be used free of charge under the Creative Commons, Non commercial, No Derivative license (CC BY-NC-ND). You can acknowledge (using reference [1]) the contribution of this package in any scientific publication dependent upon the use of the package.

To access the beta version of the DropUI software, please fill in the following form, and you will receive personalized URL by separate e-mail. All form fields are required.

[1] B. Favier, N. T. Chamakos, and A. G. Papathanasiou, “A precise goniometer/tensiometer using a low cost single-board computer”, Meas. Sci. Technol, 28 125302, 2017.