Regensburg 2019 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 68: Microfluidics (joint session DY/CPP)

CPP 68.1: Talk

Friday, April 5, 2019, 10:00–10:15, H6

Tunable stirring of the interior of biofluid microdroplets in a microfluidic channel — •Pierre-Yves Gires, Mithun Thampi, and Matthias Weiss — Experimental Physics I, University of Bayreuth, Germany

Studying dynamic changes of and within fluid droplets with bio-mimetic or biological composition, e.g. produced in microfluidic devices, is a key technique for biotechnology. However, due to their small dimensions, a controlled and gentle stirring of the droplets' interior has been very challenging. Here we report on an approach that allows for performing such a tunable stirring of microdroplets via home-made magnetic nano-stir bars. In particular, we have used a PDMS-based microfluidic junction with a hydrophobic carrier fluid to produce aqueous biofluid droplets with 10-100 microns diameter into which magnetic nano-stir bars were incorporated. By subsequent stimulation with an alternating magnetic field, nano-stir bars performed a rotational motion with tunable frequencies in the range 0.01-10 Hz. The differential effect of this stirring on particle diffusion and on the undulation of semiflexible biofilaments, i.e. microtubules, was then quantified via quantitative fluorescence microscopy to dissect thermal and active noise contributions.