A novel microfluidic device for the in situ optical and mechanical analysis of bacterial biofilms

Viable methods for bacterial biofilm remediation require a fundamental understanding of biofilm mechanical properties and their dependence on dynamic environmental conditions. Mechanical test data, such as elasticity or adhesion, can be used to perform physical modelling of biofilm behaviour, thus enabling the development of novel remediation strategies. To achieve real-time, dynamic measurements of these properties, a novel microfluidic flowcell device has been designed and fabricated for in situ analysis using atomic force microscopy (AFM). The flowcell consists of microfluidic channels for biofilm establishment that are then converted into an open architecture, laminar flow channel for AFM measurement in a liquid environment. Finite element analysis (FEA) was used to profile fluid conditions within the flowcell during biofilm establishment. Force-mode AFM was used to measure the elastic properties of mature Pseudomonas aeruginosa PAO1 biofilms as well as polyacrylamide hydrogels. Elastic moduli ranging from 0.58 to 2.61kPa were determined for the mature biofilm, which fall within the range of moduli previously reported by optical, rheometric, and microindentation techniques. These results demonstrate the validity of the microfluidic flowcell system as an effective platform for future investigations of biofilm mechanical and morphological response to dynamic environmental conditions.