In 2013, scholars of Beihang University reported in Nature's Scientific Reports a tilt angle dip-coating method to fabricate bioinspired Fibers with Gradient Spindle-knots (BFGS) using Polyvinylidene Fluoride (PVDF). Due to the multi-level cooperation of the release energy of drop coalescence along the gradient spindle-knots, as well as capillary adhesion force and continuous difference of Laplace pressure, water drops are driven to move fast directionally in a long distance on BFGS.
