Biomimetic study of rolling transport through smooth muscle contraction.

Inspired by the rolling behavior of oosperm through smooth muscle contraction of fallopian tube, a simple biomimetic experiment is devised in order to disclose the possibly mechanical transport mechanism. An interesting experimental observation demonstrates that an elastic strain gradient can be utilized to transport a soft latex bubble on a stretchable substrate by rolling. A corresponding theoretical model is established, in which an elastically three-dimensional bubble contacts adhesively on an elastic substrate subject to strain gradient. The initiation and steady-state energy release rates for such a rolling motion are achieved and analyzed. The influencing factors of rolling are found. The finding may have general implications on designing active transport systems with strain gradient.