Not to change the structure of a sample during a measurement - this goal is hard to achieve if the sample is a foam. The solution of this problem catches one's eye: the optical method of the Foam Shape Analyzer FSA10 for simple, fast, and above all non-destructive measurements with solid and liquid foams. No contact with probes, no dependence on characteristics of the foam such as electrical conductivity to name only one.

The solid foam sample is applied as a slice, the liquid foam is placed in a glass beaker or onto a glass plate before it is positioned along the optical axis. Depending on the type of foam, images are then taken with incident or transmitted light.

The software for image analysis detects pore and bubble edges respectively and calculates all other properties like pore and bubble diameter as well as its distribution, surface coverage and the fractal dimension which can be further correlated with other foam parameters.

The instrument comes with a modular design and allows easy access to the sample space. Adaptation to many sample shapes and sizes is done easily.

KRÜSS proudly announces the partnership with SOPRA, France, the leading manufacturer of spectroscopic ellipsometers for flat panel display industry.

Up to now the quality control in this sector of technology was achieved primarily by means of polarimetric measurements of the layers. But in order to gain detailed information on the surface condition of the samples, more and more the measurement of the contact angle measurement is used to supplement this information. With the help of the contact angle measurement it is possible to determine the free surface energy at any location of the sample in the same non-destructive way as in the ellipsometric process.

In a joint development project of SOPRA and KRÜSS it was possible to combine both measuring methods: the KRÜSS contact angle measurement head GH100 with a SOPRA ellipsometer. As an example, the new multiple-methods instrument tells the user very fast, if the measured inhomogeneities are caused by defective layer or insufficient cleaning procedures.

The instrument was successfully launched to the market and became an important tool in quality control of some major customers. This first fruitful cooperation prods SOPRA and KRÜSS to launch further projects aiming at developing novel integrated systems with technologies from both partners.

In no other sector of technology there is more need for fast and precise quality control as it is in the semiconductor industry. KRÜSS helps to manage the huge number of wafers to be tested in the laboratory - by contact angle measurements with our fully automatic wafer tester.

6’’ or 8’’ wafers are stored in variable cassettes accessible by a handling robot. A simple procedure in our software allows the user to define not only the drop position for contact angle measurement on the wafer surface, but also the image and optical parameters, the applied contact angle method and finally the method of surface free energy calculation. Then just another mouse click away - the robot starts to put wafer on the sample stage one by one. The whole measuring procedure is executed fully automatic for each wafer.

Afterwards decisions have to be derived from the results - and for this there are no robots available.

Please have a brief look at a full stop mark in a newspaper text. Can you imagine to dose 20-30 drops on an area this size and measure their contact angles?

Measurements like this are possible with the new Micro-Dosing System DSA100M, an innovative development specially created for extremely small samples such as hairs, welds, or circuit paths.

An innovative dosing unit produces very small drops down to a few picoliter exactly and with a precision landing. A flexible LED illumination with low thermal radiation and customizable optical system lead to an exquisite image quality. Camera systems with image acquisition rates from 25 up to 1000 fps (frames per second) are available.

High speed is a significant factor for the efficiency of technical processes like printing, pumping, varnishing, or foaming. But in many cases the substances and additives used tend to slow the process: At high speed they show unwanted surface phenomena, which lead to partially wetting, unwanted foaming or instability of produced foams or emulsions. The analysis of interfacial rheological characteristics with the new EDM/ODM module (Expanding Drop Module / Oscillating Drop Module) for the contact angle measuring system DSA100 helps to get the problems under control.

Different from pure liquids the surface tension of surfactant or polymer solutions varies due to the expansion of the surface, only to get back to a state of equilibrium after a while. This behavior is based on low mobility of large molecules. The change of surface tension depends on the degree of area change and on the speed of expansion. In interfacial rheology both phenomena are examined separately: the dependency on the degree of expansion is called interfacial elasticity, the dependency on the speed is called interfacial viscosity.

The new EDM/ODM module for the DSA100 is able to determine both parameters. By changing the volume the surface of a spherical drop oscillates. It is possible to modulate the oscillation with constant frequency and amplitude to various undulations. The most important is the sinusoidal oscillation. The response of the system is measured in two ways: By analyzing the pressure signal for the change in volume and also by optical analysis of the changing drop image, which is monitored by a video camera. As surface rheological data one receives the loss modulus, which describes the viscous characteristic, and the storage modulus as the elastic parameter.

Furthermore the EDM measurement - "E" stands for "Expanding" - is implemented in the module. A drop is rapidly expanded or contracted with a constant size after that. The change of surface tension with time, i. e. the relaxation, is analyzed. These results provide information on mobility and adsorption behavior of dissolved molecules.

With the knowledge of the surface rheological properties it is possible to strongly modify the dynamic behavior of the system on the base of molecular characteristics.

The new environmental chamber TC11 for the DSA100 line offers the needful space for large sample dimensions. Samples that were previously impossible to examine under inert gas conditions or at high temperatures find now sufficient space in an enlarged chamber with inner measures of 132 x 132 x 27 mm (l x w x h). The temperature ranges between -10 °C and 120 °C and is controlled by a circulator. The sample can be flexibly positioned from outside so the chamber doesn’t have to be opened between measurements. Also, smaller samples can be fixed with built-in clamps and do not require a smaller chamber.

The new high temperature dosing system DO3240 for the DSA100 line enables the user to dose liquids with temperatures up to 400°C. Solid samples are molten in the electrically heated cylinder and dosed in a hot condition. In combination with the high-temperature chamber TC21 measurements of contact angles and surface tensions of hot liquids become a matter of laboratory routine.