Self-sustaining peristaltic motion on the surface of a porous gel.

We report the structural color behavior of a periodic ordered mesoporous gel synchronized with the Belousov-Zhabotinsky (BZ) reaction. The structural colored concentric rings which were spatiotemporally spread out on the porous gel were observed during the BZ reaction. The color tone of the structural color, which is determined by the swelling ratio of the gel, was periodically changed. This is the first evidence that a self-sustaining peristaltic motion occurs on the surface of a gel.