Active pulsatile gels: from chemical microreactor to polymeric actuator

TL;DR

This paper presents a comprehensive study on active pulsatile BZ hydrogels, combining synthesis, experimental characterization, and modeling to optimize their chemomechanical oscillations for potential actuator applications.

Contribution

It introduces a novel two-step synthesis method for BZ hydrogels and links their oscillation behavior to medium chemistry and size, validated by theoretical models.

Findings

Oscillation amplitude depends on gel size and medium chemistry.

Optimal gel size maximizes chemomechanical oscillations.

Experimental results agree with established chemical and swelling models.

Abstract

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.