Displacement of liquid droplets on micro-grooved surfaces with air flow

We investigate experimentally the dynamics of a liquid droplet that displaces on the micro-grooved surfaces driven by a controlled air flow. A range of experiments were carried out on the surfaces which patterned micro grooves with different directions and dimensions. The velocity required to initiate droplet motion increased with the grooves' dimensions. Displacement was obtained easier on the parallel micro-grooved surfaces compare to the vertical micro-grooved surface. Then a force balance model was constructed based on the capillary force and driving force. The analytical results were well consistent with the experiments. We suggest that the force model could be exploited in a reasonable estimate for the initiation velocity on a micro-grooved surface.