There is disclosed a unidirectional liquid transport system. The system, or a liquid diode, has an array of elongate units. Each unit is defined by a surrounding fencing, and includes a region generally resembling a U-shaped micro-scale island with a proximal end on one side having an opening and a distal end on the opposite side thereof. A channel is defined between a lateral side of the island and an adjacent fencing thereof, and the channel is divergent from the proximal end towards the distal location on the opposite side thereof. The island includes a reentrant member configured to, upon contact with droplets of a liquid to be transported, initially arrest flow of the liquid and produce a pinning acting to allow building up of excess surface energy, and subsequently cause coalescence of the liquid thus converting the surface energy to kinetic energy for movement of the liquid; and surfaces of the units are fabricated on silicon wafer.