Chapter 7: Tactic Droplets at the Liquid–Air Interface

Tactic motion in nature is one of the key properties of a living organism. Similar behaviour can be observed in inanimate systems at the liquid–air interface, in which a chemical entity (droplets, particles) can be self-propped and provides artificial chemotactic motion in a gradient of concentration or temperature. In these systems the global and local Marangoni flows play important role in supporting the tactic motion of the entity. In this work, we provide a short description of existing methods utilizing the Marangoni flow to support tactic motion of an entity at the liquid–air interface by passive or active ways. We also present an alternative way to simulate fluid flow (Marangoni flow) based on dissipative particle dynamics.