System development for generating homogeneous cell suspensions and transporting them in microfluidic devices

Miniaturized biological test assays require an even distribution of the utilized cells in every single segment. For the cell dispension, two devices with a volume of about 2 milliliter were developed enabling simultaneous mixing and processing of suspensions into capillaries. These items will be used to generate homogeneous suspensions for a duration of up to one hour and distributing them with special microfluidic chips. Both devices could be easily sterilized by autoclaving and contain an agitator which is contactlessly driven with variable speed. Precise transportation of the mixed fluid in the lower microliter per minute range was realized by the use of syringe pumps. Suspensions with yeast, mammalian cells and beads were applied to investigate the efficiency of mixing and transportation as well as the effect on viability. At certain time intervals, samples were taken from the outlet, and the cell and bead content with the related viability was determined using an automated particle analyzer and counting chamber under the microscope. Yeast suspensions were handled up to two hours and hybridoma cells up to one hour without remarkable loss of viability whereby the degree of mixing was sufficient for these time periods. The results show that these modules are feasible tools for homogeneous mixing of cell suspensions, and transport through microfluidic devices allows dispensation of them into fluid segments on a microliter or nanoliter scale.