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Abstract

Dynamic wetting phenomena lack of a proper qualitative and quantitative characterization, especially at the micro and nanoscale. The project focuses on the design and fabrication of AFM tips capable of measuring forces and energies involved in wetting phenomena, differentiating between contact line sliding and pinning effects of a fluid interface. The tips geometry consists of micro-sized pillars with a groove all around at middle height. Different fabrication processes were investigated and optimized for the success of the tip preparation. These structures were finally fabricated with smooth surface walls and sharp groove edges. After fabrication on wafers, the tips were glued to tipless cantilevers, detached from the substrate, and exploited for fluid AFM measurements. Strong pinning at one edge of the groove was detected and adhesion forces in the μN range were measured. This successful and stable pinning allows effective and reproducible manipulation of interface curvature, which can be also used for targeted migration and assembly of nanoparticles trapped at fluid interfaces.

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