Arbitrary directional triboelectric nanogenerators: Advanced energy harvesting for sustainable future

Harnessing electricity from our surrounding environments offers a promising solution to the global energy crisis. Triboelectric nanogenerators (TENGs) have proven effective in capturing electrical energy from ambient sources. However, traditional TENGs typically operate in a single direction as triboelectrification occurs on fixed solid surfaces. To address this shortcoming, researchers are actively developing TENGs capable of harvesting energy from multiple directions, utilizing diverse natural forces such as flowing water, ocean waves, wind, sound, and various body movements. This review explores the recent developments of arbitrary directional freely moving particles, wind, rain, and ocean based TENGs, which can generate electrical energy from multi-directional forces as arbitrary directional energy harvesters. Furthermore, the key challenges and future perspectives for scavenging triboelectric energy from arbitrary directions are presented. Finally, the SWOT analysis (strengths S, weaknesses W, opportunities O, and threats T) has been summarized to evaluate arbitrary directional responsive TENG technologies from freely moving particles, wind/breeze movement, rainfall, and ocean waves in TENGs.