  Living materials adapt their shape to signals from the environment, yet the
impact of shape changes on signal processing and the associated feedback
dynamics remain unclear. We derive coarse-grained equations for droplets that
adjust their interfacial tension in response to signals exchanged at contact
surfaces, from the microscopic biophysics of adhesion and signaling. We find
that droplet pairs exhibit symmetry-breaking, excitability, and oscillations.
The underlying critical points reveal novel mechanisms for physical signal
processing through shape adaptation in soft active materials.
