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Computational Colloids

Analysis agarose-type hydrogel as a soil analogue

1 Sep , 2016  

Computational colloids aims to develop a pressure-sensing bacteria which will ultimately be introduced into the ground in order to synthesise biomaterials and create subsurface structures. Therefore, a uniform distribution of bacteria throughout the selected soil layer is an essential requirement.
However, before introducing and testing the bacteria in geomaterials, another compound will be used instead: an agarose-type hydrogel. This material has the ability to provide ideal growth conditions – due to the addition of nutrients into its matrix. Moreover, it allows cell motility and nutrient transport through its porous microstructure – providing a uniform distribution of bacteria cells.
Thus, experiments have been carried out in order to analyse the mechanical properties of the hydrogel. Specifically, undrained triaxial tests have been performed to identify the undrained shear strength and stiffness as well as maximum compressive strain. The results indicate that a potential layer of agarose-type hydrogel would be able to carry loads similar to the bearing capacity of soft-firm cohesive soils, but with an increased deformation.
Additionally, some samples of hydrogel with GFP-attached-bacteria (a fluorescent gene) were visualised with a fluorescent microscope and the results showed an uniform 3D distribution of bacteria cells within the material. Further, the same samples were analysed using a SEM microscope and the images confirmed the distribution of cells within the bacteria-seeded hydrodel.

Confirmation of bacteria cell distribution on fluorescent microscope (left) and SEM microscope (right)


As a conclusion, although more tests are being performed to identify the pore pressure dissipation behaviour, agarose-type hydrogel stands as a promising material for the Computational Colloids proof of concept due to its mechanical performance and ideal microbial growth conditions.
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Captions showing sample preparation and testing procedure

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