System Development for Generating Homogeneous Cell Suspensions and Transporting them in Microfluidic Components

Abstract

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.

A modular segmented-flow platform for 3D cell cultivation

“…The fluidic microsystem was always used in connection with the minispinner to guarantee the generation of homogenous cell suspension droplets (Schumacher et al, 2008;Schemberg et al, 2009; Section 2.6). It is based on milled hydrophobic microchannels of 0.1-1.6 mm inner diameter.…”

“…1B) as droplet generation module, a cell mixing module, developed as "minispinner" by iba and commercially available by cetoni GmbH had to be integrated directly in front of the fluidic microsystem in order to guarantee a homogeneous single-cell suspension and thereby a generation of homogeneous cell suspension droplets (Schumacher et al, 2008;Schemberg et al, 2009). All details of the construction and its functionality were published previously by Schumacher et al (2008). Briefly, the minispinner is used for mixing of shear stress-sensitive cell suspensions and consists of a working volume of 1.9 mL.…”

Application of segmented flow for quality control of food using microfluidic tools

“…To get reproducible fluorescence signals from the microcapsules a homogeneous mixing of the suspension is necessary. For samples in ml scale which are susceptible to shear stress a special stirrer called MiniCellMix ® was developed 27. First, the inner volume of the mixer (1.9 ml) was filled with the carrier medium to displace air bubbles.…”

Instruments in Biotechnology and Medicine

“…The volume ranges from a few milliliters (mostly laboratory scale and research; see Figure 6.112) to thousands of cubic meters (production scale), depending on the particular process (organism, product, application). By means of todays microsystem technology, it is already possible to use microfluidic-generated droplets in the nanoliter range (Figure 6.113) to cultivate and handle single cells inside for special purposes, for example, testing of individual cells against chemical stress or encapsulation to protect the cells against surrounding media [363,364]. They are often termed microbioreactors.…”