Spontaneous motion of liquid drops via self-assembled surface modification

The reactive-wetting phenomenon is investigated in this work. The nature of the wetting of liquid on solid surface of heterogeneous chemistry is postulated and later qualitatively proven. Through such understanding, a novel microfluidic device based on reactive-wetting has been proposed and studied. The device has been designed to enable divisions of minute liquid drops, without momentum transport, on flat surface designs. It is shown that multiple divisions and even tearing of one drop is possible. A physical explanation is developed to reveal the collapse of liquid film due to contributions from surface tension and the size parity in the surface design. Pragmatic aspects of the device has also been investigated. Phenomenologically, experiments has linked the kinetics of adsorption to the length and velocity of drops. The regime under which the kinetics operates can be inferred from the length and velocity of a drop. Simulation of the reactive-wetting phenomenon has been implemented and well-compared to observations in the experiments.