The motion of a water droplet on a single vertical sugar fiber is analyzed. The fiber is positioned vertically, with the droplet placed at its pending end. If the capillary force is able to balance the weight of the droplet, the droplet remains suspended at the fiber extremity. As sugar is dissolved inside the droplet, the fiber eventually breaks. Subsequently, the droplet may fall down carrying a portion of the not yet dissolved fiber, or, more interestingly, the droplet may be propelled upwards, remaining attached to the fiber. The process can then restart. The upward jump (or motion) of the droplet is caused by the capillary force exerted by the droplet on the fiber. When the fiber breaks (or becomes weakened) due to dissolution, this capillary force is no longer balanced, causing the droplet to jump upward. A phase diagram is constructed based on the droplet volume and the fiber diameter. A model has been built to assess the critical droplet volume for a given fiber diameter, above which the droplet falls. Below this volume, the droplet can move upwards along the fiber.

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