Indentation experiments on (artificial) biofilms

Field: Physical chemistry / material sciences / mechanical engineering

The project is part of a PhD project from the biofouling theme of Wetsus and will take place at PCC in Wageningen.


Biofouling occurs when microorganisms start accumulating and growing on surfaces. For protection and fixation reasons they surround themselves with a slimy layer of extracellular polymeric substances (EPS), containing all kinds of polysaccharides, proteins, cell fragments, inorganic particles, etc. This is especially unwanted on membranes as they are commonly used e.g. in (drinking) water treatment. The more biofouling reduces the water flux through the membrane the less economic the process becomes and a lot of effort is put in cleaning.

For the development of smart cleaning strategies the target needs to be known. In addition to the bacterial communities this target contains the physical structure and chemical composition of biofilms, which determine their strength and resistance against cleaning.

Project description

During my thesis research I have assembled a set of force measurements for investigation of the “strength” of artificial biofilms. This includes measurements with the shear rheometer as well as indentation experiments with the force robot and another device (same mechanism, bigger scale). In your project you will focus on the indentation experiments and exploit their full potential in the application on biofilms. The field of interest will be the differences between the different scales and how this can be used for understanding the structure of films. As a model compound alginate will be used, either in form of commercial sodium salts or of an extract from granular sludge (will be provided). Your study will start with a comparison of bulk material with films and continue with the comparison of films with different compositions. More details can be arranged following your interest.


We are looking for a highly motivated, enthusiastic and independent student ideally with a background in molecular life sciences, mechanical engineering, (physical) chemistry, or other related fields.


You feel excited about this project or still have questions? Just contact us! Natascha Pfaff and Mieke Kleijn.