Bulk nanobubbles (BNBs) are submicron gaseous domains dispersed in solutions, which are supposed to survive for several hours or even days. In recent years, there has been a rapid growth in the research and extraordinary applications of BNBs. Conventional theories based on gas diffusion and Laplace pressure, however, predicted that nanoscale gas bubbles in water should dissolve within microseconds, presenting a modern-day paradox in current nanobubbles researches. Also, it is still challenging to efficiently produce BNBs and determine their gaseous nature with the available techniques. In this review, we start from a general introduction and brief history of nanobubbles researches and revisit the current progress on the generation methods and detection techniques. Two possible formation mechanisms are suggested, and the plausibility of the proposed theories on BNBs stability is discussed with some suggestions for future studies on bulk nanobubbles.

块状纳米气泡（BNB）是分散在溶液中的亚微米气态域，应该可以生存数小时甚至数天。近年来，BNB的研究和非凡应用得到了快速增长。然而，基于气体扩散和拉普拉斯压力的传统理论预测，水中的纳米级气泡应在几微秒内溶解，这在当前的纳米气泡研究中提出了现代悖论。而且，利用现有技术有效地生产BNB并确定其气态性质仍然具有挑战性。在这篇综述中，我们从对纳米气泡研究的一般介绍和简要历史入手，并回顾了纳米气泡的产生方法和检测技术的最新进展。建议了两种可能的形成机制，