Microfluidic dissolved oxygen gradient generator biochip as a useful tool in bacterial biofilm studies

Abstract

A microfluidic chip for generation of gradients of dissolved oxygen was designed, fabricated and tested. The novel way of active oxygen depletion through a gas permeable membrane was applied. Numerical simulations for generation of O(2) gradients were correlated with measured oxygen concentrations. The developed microsystem was used to study growth patterns of the bacterium Pseudomonas aeruginosa in medium with different oxygen concentrations. The results showed that attachment of Pseudomonas aeruginosa to the substrate changed with oxygen concentration. This demonstrates that the device can be used for studies requiring controlled oxygen levels and for future studies of microaerobic and anaerobic conditions.

Critical review on biofilm methods

“…Depending on the geometry of the flow chamber and the flow rate, the flow may be laminar or turbulent, influencing the distribution of nutrients and dismissal of waste products, and ultimately biofilm structure (Lewandowski & Beyenal, 2014;Skolimowski et al, 2010;Stoodley et al, 1998).…”

“…Custom-made microfluidic devices using PDMS techniques for manufacturing have been employed by several groups, e. g. systems where compartments are separated by a semi-diffusible membrane to allow the study of nutrient or signal molecules Skolimowski et al, 2010Skolimowski et al, , 2012, a system employing a micro-structured surface to study filamentous biofilm (steamer) formation (Hassanpourfard et al, 2014), a simple device for easy microscopic investigations of biofilms using reflection confocal microscopy (Yawata et al, 2010), a system to study the influence of shear stress due to changes in flow conditions (Salta et al, 2013), a system to allow the assessment of the effects of antibiotics in an on-line mixing system (Terry & Neethirajan, 2014), and a system to online study the development of biomass (biofilm thickness) (Meyer et al, 2011). The general usability of microfluidic techniques is, however, still limited by the difficulty of the methodology and the skills needed for successful employment.…”

Design Criteria for Generating Physiologically Relevant In Vitro Models in Bioreactors

“…Most microfluidic devices reported in literature are made of PDMS, a gas permeable elastomer [30,[67][68][69]. Therefore, the computational model presented in Section 4.2 can be refined by considering the inward oxygen flux through PDMS, which is given by the following expression [67,70]:…”

Microplatforms for Gradient Field Generation of Various Properties and Biological Applications

“…14 The concept of such gradient chips is applicable not only for reagent concentrations but also other properties that can stimulate cells such as electromagnetic fields, 14 temperature, 15 materials, 16 and gaseous molecules. 17 Earlier devices for gradient generation used pipette tips, 18 gel reservoirs, 19 and diffusion chambers, 20 which were unable to maintain spatiotemporal control of concentration gradient profiles at single-cell scale resolutions (10-100 µm) or maintain the gradient fields for a long duration (days) because the main mechanism of gradient generation relied only on diffusion, and thus continuous changes in gradient profiles were unavoidable. To overcome such problems, the microfluidic gradient generator was developed in 2000 ( Fig.…”