Walking out of the house in the morning, the air is humid, and fine water drops are hung on the grass leaves. You may not think that these tiny condensation are becoming the source of inspiration for scientists to solve the global water problem. The clear water flowing from the faucet may one day come not from the underground water pipe, but from the invisible fog in the air.

In many arid areas, the difficulty of obtaining water is not only a problem of "thirst", but also related to farming, sanitation and life extension. However, the water vapor content in the air is often ignored. Take the coastal desert as an example. The sand dunes are hot and dry during the day, but they are often shrouded in thick sea fog at night. Scientists have found that these fogs are huge "invisible reservoirs". As long as they can be collected efficiently, they can provide new water sources for water-deficient areas.

The concept of fog collection is not complicated: when moist air touches a cold surface, water molecules will condense into water droplets. The problem is how to "please" the water molecules in the air efficiently. Although the traditional metal mesh or plastic mesh can intercept some droplets, the collection efficiency is not ideal. As a result, researchers began to imitate the "masters" of nature-such as the nano-scale beetle back shell, or the tiny structure at the tip of cactus thorns. The surface of beetle's carapace has hydrophilic and hydrophobic areas at the same time, so that water droplets can quickly polymerize and roll off; The cone-shaped structure of cactus thorns can guide the condensed water droplets to the roots.

Nowadays, some laboratories have transformed these bionic designs into real materials: polymer fibers with special coatings, films with micro-nano grooves, and even portable "fog curtains" that can be curled. They are like silent collectors, which can be quietly collected into a cup of drinkable water when the air humidity is right. More interestingly, researchers are exploring embedding this technology into buildings-for example, installing invisible mist collection films on walls and roofs, so that a house can generate part of domestic water by itself. Imagine that in the future kitchen, in addition to water pipes, there may be a wall that can "breathe" and silently produce several liters of drinking water every day.

The potential of this technology is not limited to human life. For agriculture, mist collector can provide micro-irrigation for plants without additional energy; In remote areas, it may become a life supply for travelers or herders. Even in extreme environmental exploration, such as desert research stations or alien migration bases, the ability to "squeeze" water from the air may become the key to survival.

However, taking water by fog is not magic, it depends on the existence of air humidity. In the hot period of the desert at noon, it may not collect water, but at night when the fog is thick, it can show amazing efficiency. For this reason, the future development direction will not only be material optimization, but also the combination of weather prediction and intelligent control, so that the fog collector can be automatically opened or closed at the most appropriate time.

When we are used to getting water by turning on the tap, it is difficult to realize that air is actually a neglected "ocean". Perhaps in the future, the city's water resources will be redrawn: underground water pipes and air collection membranes coexist, and fog nets on roofs and hillsides are quietly running. Every drop of water is no longer just from the visible river, but from the invisible clouds between our breaths. If people used to dig wells to draw water, then in the future, we may just stretch out a thin "net" and let the air offer us a cup of morning dew.

（Writer：Haicy）