Using light to guide the self-sustained motion of active gels.

We undertake the first computational study to determine the effect of light on polymer gels undergoing the Belousov-Zhabotinsky (BZ) reaction. The BZ gels are unique materials because they can undergo rhythmic mechanical oscillations in the absence of external stimuli. The BZ reaction, however, is photosensitive. Via simulations, we demonstrate that the interplay between the chemoresponsive gels and the photosensitive reaction can cause millimeter sized BZ gels to exhibit autonomous, directed motion or reorientation away from 4 the light. In effect, we show that these synthetic BZ "worms" display a fundamental biomimetic behavior: movement away from an adverse environmental condition, which in the context of the BZ reaction is the presence of light.