Regensburg 2022 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Poster 1

BP 7.12: Poster

Monday, September 5, 2022, 18:00–20:00, P1

Controlling size, phase transitions, and reactions in microfluidic double-emulsion droplets — •Paula Girones Paya, Sebastian W. Krauss, and Matthias Weiss — Experimental Physics I, University of Bayreuth

Double-emulsion based assays have been widely used in a large number of experiments such as in bio-inspired microreactors or in direct evolution assays. Despite the advanced techniques that have been developed to produce picoliter-sized droplets, a better manipulation of the droplet interior remains a challenge. Here, we demonstrate how hundreds of double emulsion droplets, trapped in a microfluidic sieve, can be grown and shrunk by controlling the salt concentration in the carrier liquid. Alternating the osmotic pressure leads to a rapid and reversible volume change of the aqueous droplet interior, resulting in a reversible phase separation of an enclosed binary fluid. The phase separation is shown to be a versatile tool to control, for example, the dissociation and re-association of double-stranded DNA or to monitor an enzymatic reaction via a pH sensitive fluorescence reporter.