Wind has come to be considered as an attractive energy source due to its abundance, ubiquity, and sustainability in nature. When an energy harvester driven by wind is miniaturized with high-power and robustness, it can be useful for self-powered systems of mobile electronic devices. In this work, a vertically stacked triboelectric nanogenerator (VS-TENG) is investigated. When wind is introduced into the air gap of the VS-TENG, a thin and flexible polymer membrane repeatedly comes in contact with and separates from upper and lower electrodes. This thin device structure makes the VS-TENG suitable for vertical stacking without bulky volume. Vertical stacking not only provides multiplied output power via parallel stacking but also enables utilization of bi-directional wind by a cross stack. (C) 2014 Elsevier Ltd. All rights reserved.