By Jennifer Chu

Feeling thirsty? Why not tap into the air? Even in desert conditions, there exists some level of humidity that, with the right material, can be soaked up and squeezed out to produce clean drinking water. In recent years, scientists have developed a host of promising sponge-like materials for this “atmospheric water harvesting.”

But recovering the water from these materials usually requires heat — and time. Existing designs rely on heat from the sun to evaporate water from the materials and condense it into droplets. But this step can take hours or even days. 

Now, MIT engineers have come up with a way to quickly recover water from an atmospheric water harvesting material. Rather than wait for the sun to evaporate water out, the team uses ultrasonic waves to shake the water out.

The researchers have developed an ultrasonic device that vibrates at high frequency. When a water-harvesting material, known as a “sorbent,” is placed on the device, the device emits ultrasound waves that are tuned to shake water molecules out of the sorbent. The team found that the device recovers water in minutes, versus the tens of minutes or hours required by thermal designs.

“People have been looking for ways to harvest water from the atmosphere, which could be a big source of water particularly for desert regions and places where there is not even saltwater to desalinate,” says Svetlana Boriskina, principal research scientist in MIT’s Department of Mechanical Engineering. “Now we have a way to recover water quickly and efficiently.”

Boriskina and her colleagues report on their new device in a study appearing today in the journal Nature Communications. The study’s first author is Ikra Iftekhar Shuvo, an MIT graduate student in media arts and sciences, along with Carlos Díaz-Marín, Marvin Christen, Michael Lherbette, and Christopher Liem.