Communication between hydrogel beads via chemical signalling

In this work, we demonstrate chemical communication between millimetre-sized soft hydrogel beads in an aqueous environment. Silver cations (Ag⁺) and the Ag⁺ chelator dithiothreitol (DTT) are used as signalling molecules. By exploiting their interplay, we conduct a series of 'conversations' between millimetre-sized beads. The communication process is monitored by tracking the response and behaviour of a central bead. This bead is loaded with the enzyme urease and has the ability to undergo a change in colour associated with a change in pH. Competitive communication between three beads, whereby the central bead receives two competing signals from two senders, is shown. We believe that our hydrogel-based system demonstrates an advance in the communication capabilities of small soft matter objects.