KRÜSS at Analytica 2010 in Munich

“All of the halls were bustling with activity” – stated Prof. Dr. Horst Domdey, the spokesman of the Bavarian Biotechnology Cluster, in the Final Report on Analytica 2010. The increase in the number of visitors was also noticed on the KRÜSS fair stand. KRÜSS’s appearance attracted a large number of interested specialists. The fair team was permanently involved in discussions, in explaining video presentations of measuring sequences and in demonstrating two new products: The contact angle measuring module TVA100 for drop measurement in reflected light and the foam measuring instrument DFA100 (an application report can be found here).

The DFA100 was particularly favored by the visitors – some of whom had come especially to Munich because of it. They were chiefly impressed by its compactness and the rapid changing of the measuring tools.

The top view distance measurements with the TVA100 mainly appealed to visitors who were looking for measuring techniques for sample surfaces that were either concave or located in recesses. The guests also included representatives from the biotechnology branch, which was the main focus of this year’s trade fair. 

The DFA100, the first instrument in this product group, profits from many years of intensive involvement with the subject of foam – and from KRÜSS’s know-how in interfacial chemistry and image analysis.

For the last 60 years KRÜSS has developed instruments for studying surface-active substances – a branch of science that is closely related with questions related to the formation and stability of liquid foams.

The generation of foam and the visual determination of its height present no real challenge. However, the challenge lies in performing both of them reproducibly. There are numerous foam measurements methods – with no fewer than three different standards describing foam height measurement according to Ross-Miles. Data for limited stability ranges, instrument-specific measuring quantities and the results from individually constructed special apparatus make it difficult to compare results from different places. In addition, foam generation takes place under undefined variables and processes in many instruments. Right from the start KRÜSS had the aim of developing applicable methods that could be used as standards for foam generation and measurement and which would make it possible to compare foams of different structures, stabilities and origins with one another according to scientific criteria.

About 20 years ago two reputable companies made first approaches for cooperation on the subject of foam. That this was initially not followed up lay mainly on the technical situation in those days. A precise foam generation technique and a suitable optical sensor system were not yet available at a reasonable price.

Subsequent contacts with foam experts were milestones on the way to the KRÜSS instrument. Prof. Exerowa from Sofia presented an apparatus that already used a foam generation technique involving a glass frit. Contact with MIR Chem was very informative with respect to foam structure. Prof. Plath’s group found in metastable foam bubbles a self-similar structure of Apollonius’ circles, whose fractal dimension was determined by image analysis.
In 2005 KRÜSS invited foam experts from different fields to a Day of Foam. Prof. Lunkenheimer from the Max Planck Institute in Golm presented a foam measuring instrument to the guests that combined good foam generation reproducibility using a defined gas input (volume flow and amount) with a convincing evaluation method. The two parameters Deviation Time (tdev) and Transition Time (ttr) oriented themselves on universal decay kinetics of liquid foams and divided the decay curve into three sections, each of which with its own assigned decay mechanism: 1. Drainage; 2. Drainage with simultaneous decay; 3. Decay after completed drainage.

Based on Prof. Lunkenheimer’s findings, Torben Schörck, qualified physicist and Product Manager for foam analysis with KRÜSS, and Development Manager Dr. Thomas Rauch (Dipl. Chem. in Physical Chemistry) started with the development of a foam measuring instrument. They produced an extremely practical instrument. Foam is generated by a flow-controlled stream of gas through a filter plate as standard. The measurement of the foam and liquid levels takes place online using a cell sensor with high time and image resolution. Thanks to its modular construction, differently-sized columns and different foam generation methods (gas flow or stirring) can be exchanged very quickly, cleaned and even used in parallel.

The quality and versatility of the DFA100 is the result of our long involvement with the subject of foam. In the future we plan to record foam properties with other sensor methods, such as conductivity measurement, and to integrate optical foam structure measurements.

From now on foam measurements will extend the wide range of services provided by KRÜSS – in the form of the provision of competent customer advice and by carrying out contract measurements in our Surface Science Lab.