Design, fabrication, and testing of a multichannel microfluidic device to dynamically control oxygen concentration conditions in-vitro

Abstract

Multilayer microfluidic devices were designed and fabricated such that an array of different oxygen concentrations could be applied to a testing area in any desired sequence and with unconstraint application times. The principle of flow resistance dictates that a large channel length will impose a larger resistance and therefore a larger reduction in flow rate versus a shorter channel length. To exploit this feature, the microfluidic device employs a fluidic resistance network composed of an array of predetermined variable length channels to generate different oxygen to nitrogen flow rate ratios, i.e. different oxygen concentrations. Standard lithographic techniques were used to fabricate the microfluidic devices, using highly gas permeable silicone rubber (polydimethylsiloxane (PDMS)). The stacked microchannel architecture, channel dimensions, and layer thicknesses in the device were optimized for rapid diffusion and saturation of 02 N2 mixtures into the testing areas. The oxygen concentration was dynamically monitored using polymeric fluorescence-based oxygen sensors integrated into the device. By altering oxygen levels over time, this device aims to selectively build up biofilms on the artificial tooth substrate as the process occurs in-vitro. A study concerning this application is also presented.