High precision measurement of surface tension/pressure

The Kibron solution is a combination of the DuNuoy-Padday et al. ‘Maximum Pull Force Technique’ and Kibrons sensor, a unique ultrasensitive microbalance.

With the aim of being able to provide the users of Kibron equipment  the most precise  determination  of surface pressure, we developed a new microbalance, with a resolution of better than 2 micrograms. This sensitivity was then combined with the "Maximum Pull Force"  principle. In this technique a probe is first immersed into the interface and then slowly pulled out, while recording the weight of the meniscus (liquid adhering to the probe). At some point the probe detaches from the interface and this is the force used to calculate surface tension.

Importantly, unlike for both the Wilhelmy plate and duNuoy ring method, there is no error due to buoyancy and thus no need for any correction. Further, the easiest way to calibrate the instrument is to use a liquid with known surface tension. The results speak for themselves. In the following the accuracy and precision of the Kibron sensor is demonstrated by the data for solvents with a broad range of known surfaces tensions, measuring each solvent five consecutive times and analyzing the results by common statistical means (see below). A comparison of the mean surface tension values and the literature values reveals an excellent agreement.
 

















A line has been fitted to the above data (figure below), giving a correlation coefficient of 0,999 and demonstrating the excellent accuracy of the Kibron sensor throughout this surface tension range.