Oscillating chemo-mechanical Belousov-Zhabotinsky (BZ) hydrogels

Yoshida [JACS 1996] developed a gel that undergoes cyclic swelling and deswelling without external stimuli. This self-oscillating gel undergoes an oxidation-reduction cyclic reaction, leading to a cyclic change of solubility of the gel. We present a new synthesis technique, offering high modularity in the gel composition and shape. We present simple experimental techniques to characterize the properties of the spherical BZ gels, such as their elasticity, timescale of swelling, density and catalyst content. Moreover, we find that a single spherical BZ gel needs to be larger than a critical size to chemically oscillate, thereby limiting the amplitude of its mechanical oscillation. We finally show how the remarkably high sensitivity of the BZ gel to its chemical environment can be harvested to enhance its actuation.