Controllable and versatile self-motivated motion of a fiber on a hot surface

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A polymer fiber can spontaneously move and deform continuously when it is placed on the top of a hot surface, driven by its rapidly varying and inhomogeneous thermal expansion. The erratic movement of the fiber is usually very complex and hard to be controlled and modeled. In this article, by introducing small kinks on the end of a straight polymer fiber, we created an energy barrier to system when it rolls, and consequently, it can roll unidirectionally on a hot surface or continuously shuttle back and forth, determined by the kinking angle and the size of the kinked segment. We have further developed a quantitative model to predict the transition of different modes of the thermally driven self-motivated motion of the fiber. The theoretical predictions agree well with experiments. Our investigations in this study have uncovered a general and facile strategy for tailoring the modes of self-motivated motion of a system through introducing energy barriers to it.