Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Poster Session II

CPP 25.6: Poster

Dienstag, 2. April 2019, 14:00–16:00, Poster B1

Role of pH in Micro-Swimming — •Nadir Möller and Thomas Palberg — Institut für Physik, Johannes Gutenberg-Universtät Mainz, Staudingerweg 7, 55128 Mainz, Germany

Modular micro-swimmers are self-assembled systems of colloids that are able to directionally traverse in a low Reynolds number environment after assemlby. In our modular micro-swimmer, a settled ion exchange (IEX) sphere exchanges residual Na+ ions for H+ and thus generates a pH-gradient. This gradient in turn induces a diffusion-electric field which drives an electro-osmotic solvent flow along the substrate. The flow assembles dispersed cargo spheres, which, once assembled break the flow symmetry and set the formed complex in motion. While a comprehensive characterisation of swimmer trajectories, speeds and stability as a function of experimental boundary conditions has been performed, and a theoretical model has been developed, the key input of modelling, i.e. the pH gradients, are available only in approximations. To gain insight of the influence the pH has on the particles motions, we utilize a home-built setup for pH-micro-photometry. This method can be employed in a variety of other systems for characterization of microfluidic and chemical attributes of electro-osmotic-driven particles.