Manipulating the dynamics of active emulsions*

Precise control and manipulation are crucial to various applications of active matter. For example, in guidance applications as in active microsensors, microreactors with targeted release or microfluidic droplet logic, we need to know and control the rules by which such entities can be guided, follow external stimuli and control their stability.

Nematic and isotropic oil droplets in aqueous surfactant solutions are well-controlled artificial active system with easily accessible tuning parameters such as temperature, liquid crystalline order or bulk viscosity. These active emulsions exhibit many properties such as wall guidance, chemotaxis, autochemotaxis, as well as tunable swimming dynamics. We demonstrate how the motion of the droplets can be controlled by topographical guidance, droplet topology and chemical gradients, and show avenues for technical application by adding internal compartments.