Dynamics of Morphological Wetting Transitions on Topographic Substrates

• Applicant: Professor Dr. Ralf Seemann
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2004 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5425482

We propose to exploit the variety of liquid morphologies forming on topographically structured substrates for manipulating small amounts of liquids on that substrate (open microfluidics). Using the electrowetting effect, we plan to transport liquids on a substrate bearing appropriate steps and grooves, by switching between various equilibrium morphologies of the free liquid surface. The particular advantage of topographic substrates is the variability in the Laplace pressure of the emerging liquid morphologies, such that liquid may be taken even from a zero pressure reservoir. We want to study the impact of a variety of parameters on the liquid morphologies, such as the applied (ac-) voltage, its frequency, the thickness of the insulating substrate coating, and the topography of the substrate. Particular emphasis will be on the interplay of the intrinsic deformation of the surface profile due to electric fields in the vicinity of the contact line and the external deformation due to the confinement in a groove. The liquid morphologies will be observed using atomic force microscopy and confocal fluorescence microscopy.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1164: Nano- and Microfluidics: Bridging the Gap between Molecular Motion and Continuum Flow
• Major Instrumentation: Scanning force microscope
• Instrumentation Group: 5091 Rasterkraft-Mikroskope