  We report on a synthesis protocol, experimental characterization and
theoretical modeling of active pulsatile Belousov-Zhabotinsky (BZ) hydrogels.
Our two-step synthesis technique allows independent optimization of the
geometry, the chemical, and the mechanical properties of BZ gels. We identify
the role of the surrounding medium chemistry and gel radius for the occurrence
of BZ gel oscillations, quantified by the Damkohler number, ratio of chemical
reaction to diffusion rates. Tuning the BZ gel size to maximize its
chemomechanical oscillation amplitude, we find that its oscillatory strain
amplitude is limited by the timescale of gel swelling relative to the chemical
oscillation period. Our experimental findings are in good agreement with a
Vanag-Epstein model of BZ chemistry and a Tanaka Fillmore theory of gel
swelling dynamics.
