Oscillating chemical reactions enable communication between responsive hydrogels

Responsive hydrogels can sense environmental stimuli and respond as actuators by expelling water and changing shape. In this Letter, we develop theory to demonstrate that groups of responsive hydrogels can also communicate with each other, by utilizing the effect of elastic deformation on chemical reaction dynamics. Specifically, we consider a system of two spatially separated chemically responsive hydrogels suspended in a solution in which a Belousov-Zhabotinsky (BZ)-type reaction occurs. Solving for the gel dynamics with the transport of solvent through the poroelastic network and the chemical kinetics, we show how the periodic swelling-deswelling oscillations of each gel can become coupled, and how this coupling can be exploited to send signals from one gel to the other via mechanical manipulation of the sender that affect the local (and thus global) frequency of oscillation.