Benjamin G. Hawkins, Jayne B. Morrow, Samuel P. Forry


In this work, we present the development of a microfluidic system to reproduce standard Pseudomonas biofilms, as defined by ASTM International, and use this platform to investigate the dependence of biofilm organization on fluid shear rate at the biofilm/media interface. Specifically, we aim to develop microfluidic measurement techniques that can be directly compared with (and inform the results of) conventional microbial assays. In addition to cell enumeration as defined in the ASTM standard, several numeric metrics, such as mean diffusion distance and fractal dimension, have been defined for biofilm structure based on analysis of three-dimensional reconstructions from confocal laser-scanning microscopy images. These analytical techniques will be used to assess the quality of biofilms grown in both macro- and micro-scale culture environments and their similarity to the established standard.


Microfluidic devices have long offered a number of significant advantages, such as small reagent volumes and parallelizable operation. In addition, microfluidic techniques afford a level of control over experimental conditions, such as spatial and temporal modulation of shear environment and nutrient concentration, which is not achievable in conventional culture systems.  Fluid shear, specifically, has been shown to significantly alter biofilm composition and morphology. We utilize the control offered by microfluidics to modulate fluid shear combined and numeric image analysis techniques to obtain quantitative results for the impact of fluid shear on biofilm morphology.