Use of the Freely-Swimming, Serratia Marcescens Bacteria to Enhance Mixing in Microfluidic Systems

Mixing has become a challenge in micro-fluidic systems because of the low Reynolds number in micro-channels. The method which is implemented in this paper is to use freely-swimming bacteria to enhance the mixing process. Accordingly, the Serratia marcescens bacteria were used for this matter. The mixing performance of the system is quantified by measuring the diffusion rate of Rhodamine B in a particular section of a channel connected to a chamber with varying Rhodamine B concentration. The concentration of Rhodamine B was measured using the Laser Induced Fluorescence (LIF) technique. The channel is in the form of a pipe and is closed on the extending side. In this paper, it is demonstrated that the corresponding diffusion coefficient can be augmented by bacterial participation and that this augmentation can be continued for several hours, depending on the environmental conditions. Additionally, it is shown that the mixing process reacts in response to modifications to the chemical environment of the system, which in turn affect the metabolic activity of the bacteria. Also, a 30 mM glucose buffer was used to show the impact of food on the performance of the bacterial system. It is thus shown that the existence of glucose increases the mixing ability of bacteria.