In order to meet the diverse requirements of nature, natural materials are often hierarchically structured. The mechanical properties of these materials are difficult to obtain with common engineering materials. However, a synthesis of materials with more than three hierarchical levels would be advantageous. One approach is to use and shape a suitable bio-template that is already hierarchically structured and transferring it to an engineering material.1 Besides fungus, plant or animal tissue, extracellular bio-materials such as exopolysaccharides (EPS) produced by microbes possess such structuring.
Microbes and their excreted EPS are commonly known as biofilms. They are normally unwanted in technical processes due to the risks of clogging or unwanted infection. External conditions such as nutrient availability or forces exerted on the biofilm e.g. the fluid flow, are affecting biofilm growth.2 Controlling the flow rate and a flow guiding scaffold, results in specific biofilms and thus tailored EPS super-structures. In order to better understand 3D biofilm formation, we investigate quasi-2D biofilm formation. We are using microfluidic cells, filled with varying obstacle arrangements, as growth chambers. The entire chamber is observed by a Schlieren-apparatus, which enhances the visibility of the so-called EPS-streamers, attaining a resolution of ten microns. Via filtering of the transmitted light, differences in the refractive index and thus EPS are visualized in this Schlieren setup.
The knowledge of the 2D biofilm formation, enables us to structure specific 3D biofilms. Serving as a bio-template, they will be transformed into composite biopolymer/ceramic engineering materials by precursors.1 Through this approach we aim of synthesizing ceramic components that feature the structure-derived characteristics of natural materials.