  The experimental control of synergistic chemomechanical dynamics of
catalytically active microgels (microreactors) is a key prerequisite for the
design of adaptive and biomimetic materials. Here, we report a minimalistic
model of feedback-controlled microreactors based on the coupling between the
hysteretic polymer volume phase transition and a volume-controlled permeability
for the internal chemical conversion. We categorize regimes of mono- and
bistability, excitability, damped oscillations, as well as sustained
oscillatory states with tunable amplitude, as indicated by experiments and
representable by the FitzHugh-Nagumo dynamics for neurons. We summarize the
features of such a colloidal neuron in bifurcation diagrams with respect to
microgel design parameters, such as permeability and relaxation times, as a
guide for experimental synthesis.
