Biomimetic surface engineering for sustainable water harvesting systems

Freshwater scarcity is becoming a global issue due to changing climatic conditions, which has stimulated the development of all-weather water harvesting technologies. Recent advances in regulating surface properties to tailor water capture/release behaviours have attracted increasing attention for water harvesting applications such as fog/dew harvesting, moisture harvesting, and solar evaporation. This Review provides an overview of the design of surfaces and the manipulation of active components to tune the behaviour of water droplets in different water harvesting systems. Taking inspiration from nature, we present a critical survey of the surface wettability, structures, and compositions used by various insects and plants to manage their water demands. We summarize the latest progress in developing desired surface properties and strategies to advance key processes in water harvesting such as droplet nucleation, growth and removal, vapour sorption–desorption, and evaporation. The challenges and opportunities to further develop a sustainable water harvesting system, encompassing both fundamental research and practical implementation, are highlighted. This Review presents an overview and analysis of biomimetic engineering principles and strategies for developing unique surface properties to design all-weather, portable water harvesting systems. It discusses key processes involved in water harvesting and proposes a framework for designing next-generation sustainable systems to alleviate freshwater scarcity.