Q-Sense software, QTools & QSoft

 

Q-Sense E4 includes two software packages; QSoft 401, which is used to acquire data during measurements and QTools 2.0, used for presentation and analysis of data. QTools has a mathematical tool that enables extraction of viscosity, elasticity and thickness of soft films under certain assumptions. It is also possible to fit data to kinetic models.

 

QTools

To present and analyse your QCM-D data you need QTools. It includes a powerful mathematical model in order to extract viscoelastic properties of thin films and also to obtain accurate thickness information of soft films that do not obey the Sauerbrey relation.

Plot diagrams
In QTools you may adjust and present data in many different ways. In the figure below, the data has been normalised (i.e. the overtones and have been divided by overtone number). Thin and rigid films show the same response on all overtones, when the Sauerbrey relation is valid. However when the response in normalised overtones differ, you are outside the Sauerbrey region and more powerful tools are needed. In the figure below this can be seen when the adsorption increases over time; the frequency response differs more and more and the dissipation rises.

 

 

Modeling features

The main feature of QTools is the mathematical modelling tool. It is possible to make a mathematical fit based on a model developed by Voinova et al. Under the assumption that the film is homogenous you may extract the thickness, viscosity and elasticity of thin films as well as fitting to kinetic models. Multiple frequency and dissipation data are required, preferably from three frequencies or at least two.

 

In the model window above, all parameters are set. While clicking on 'Fit' the program will calculate a possible solution. In this case you also get three output columns; viscosity, elasticity and thickness (the density is kept on a constant level). For the example above it looks as follows:

 

There is much more to say about QTools - please contact Q-Sense for more information of the many possibilities.

QSoft

In QSoft you can adjust all options prior measurements but also during measurements. Some of the features include:

 

• Real time measurements. The curves are plotted when the instrument collects data directly on the screen. You can see the effect of changes that are conducted during measurements immediately.

 

• Liquid or air measurements. As the quartz crystal is much more dampened in liquid media a different sampling time is needed in order to obtain a good mathematical fit.

 

• Temperature measurements. The temperature is set in the software which allows temperature ramp measurements.

 

• Sweep function. The electronics unit handles frequencies between 1 and 70 MHz. A measurement starts by conducting a frequency sweep where the resonance peak for a new crystal is easily found.