Shown here is a water droplet in oil. Microtubule bundles in the water phase form an active nematic on the inner surface of the oil-water interface of an emulsion droplet.
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The fast streaming nematic defects on the inner surface of the emulsion droplet provide a mechanism which propels the droplet when squished between two plates of glass.
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We can change the surface tension of the vesicle by inducing a hypertonic stress. The outward flow of water from the vesicle results in excess membrane containing the active nematic. The four +1/2 defects in the system then force filopodia-like protrusions which extend out of the vesicle.
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The active nematic confined to the inner leaflet of the lipid bilayer of a vesicle restricts the number of defects to 4x +1/2 defects. They alternatively oscillate between a tetrahedral and planar configuration. In this video, we track the defect positions on the surface of the vesicle using confocal microscopy.
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