Controlled movement in fluids is essential to the function of living systems. The desire of scientists to understand such complex motility in great detail, for over two centuries, has furthered our understanding of its intricacies. At the microscale, movement has been essential to the survival of all life, where individual cells can react to various chemicals by moving in a pre-programmed manner. This phenomenon is known as chemotaxis. To emulate such structures and processes we present micro-vehicle droplets, that can move in response to chemical gradients (chemotaxis), light (phototaxis) and electric fields (electrotaxis).

Additionally, we present chemotactic droplets which interact intimately with their fluidic system, offering the ability to make decisions, perform chemical reactions, carry out dynamic sensing-reporting and implement damage detection-repair. Such self-directed, multi-purpose movement of micro “vehicles” offers many intriguing opportunities in the microfluidics field. This could potentially stimulate novel research in open droplet microfluidic devices, where the driving force for movement is dictated by the chemistry of the fluidic system itself, rather than through external control by the user.