Forming self-rotating pinwheels from assemblies of oscillating polymer gels

Using computational modeling, we show that millimeter-sized polymer gels undergoing the self-oscillating Belousov-Zhabotinsky (BZ) reaction can spontaneously self-aggregate to form macroscopic, self-rotating pinwheels. Notably, we find that the system is bistable and the formation of the pinwheels depends on initial random fluctuations. The pinwheel formation can, however, be promoted by tailoring the local concentration of the activator for the BZ reaction. Furthermore, we demonstrate approaches for controlling the chirality of the pinwheels' motion. These materials could form simple self-propelled machines, such as gears, that perform autonomous work.