Active Droplets supplied with Energy and Matter

Chemically active droplets provide simple models for cell-like systems that can grow and divide. They are maintained away from thermodynamic equilibrium and host chemical reaction cycles, which correspond to a simple metabolism. We consider two scenarios of non-equilibrium driving. First, droplets are driven via the boundaries of the system by external reservoirs supplying nutrients and removing waste. Second, droplets are driven by chemical energy provided by a fuel in the bulk. We discuss the conservation of energy and matter as well as the balance of entropy. We use conserved and non-conserved fields to discuss the rules governing energy and matter supply. Using an effective droplet model, we explore droplet stability and instabilities leading to droplet division. A key finding is that that droplet division occurs quite generally in active droplet systems. Our work reveals that life-like processes such as metabolism and division can emerge in simple non-equilibrium systems that combine the physics of phase separation and chemical reactions.