
Profile Analysis Tensiometer PAT1M
This tensiometry method goes back to the methodology called ADSA, which was developed by Neumann and his team after the modern video technique became available and computers were powerful enough for managing large computational work in a reasonable time. Now, this method of determining the surface and interfacial tension from the profile of pendent and sessile drops is the most frequently used technique and various commercial instruments are on the market. Our PAT1M is based on this methodology and due to its modular architecture, compact design and highly accurate and efficient software it is one of the best instruments of this type worldwide. The process of measurement consists of the image acquisition of the drop/bubble profile, its digitalization and final fitting by the Gauss-Laplace equation. A fully computer controlled dosing system allows to perform pre-programmed measurements with any type of protocol, including constant drop volume or constant drop surface area. Changes of the drop/bubble area according to a given protocol, as it is the case for relaxation experiments, is also possible, i.e. the response of the interfacial layer to harmonic or transient area perturbations can be recorded and hence the surface dilational visco-elasticity determined. The method has many advantages over others, most of all it can be applied to liquid/gas and liquid/liquid interfaces, requires small amounts of liquid, and the temperature control is possible in a rather broad range. Even high temperature experiments are feasible with a special temperature cell.