The "air hand-washing device" developed by students from Zhejiang University. 

A group of senior students from Zhejiang University have successfully developed an "air hand-washing device." The device utilizes an infrared ray induction system, which detects the presence of hands. A tap then sprays a light water mist along with a strong gust of air, which the students have proven to be nearly as effective as traditional hand-washing. However, the device uses only 10 percent of the water that regular hand-washing does.

Li Qizhang, a member of the team that developed the device, told a reporter from thepaper.cn that a model of their device has already been installed in a classroom building at the university, and that the results have been satisfactory. The students have set up a company to further promote their product. 

In 2014, a student named Chen Puyang first came up with the idea while washing his hands in the school cafeteria. Washing one's hands uses a lot of water, Chen thought. Would it be possible to replace the water with air?

Others may not have given the question a second thought. However, for Chen and Li, who were studying fluid mechanics, this constituted a brilliant idea. 

Soon, Chen, Li and several classmates embarked on the project. The design of the device required knowledge from a variety of different majors, so the R&D team eventually came to be composed of seven students from various majors. 

"We put different kinds of dirt on our hands and washed them with water. It turned out that 95 percent of water is used to flush away the dirt; only 5 percent is used to dissolve it. If we washed with only air, then the dirt on our hands would not dissolve. So we decided to use a fine water spray to complement the air. That way, the dirt is carried away by air and dissolved by water," explained Li.

After a year of research and experimentation, the team came up with a gravity-driven hand-washing device whose reliance on water was minimal. The user stands on a platform in front of the device, which sinks because of the weight of the user. The gravity exerted by the user pulls the piston through a pulley block, and a gust of air is generated through air extrusion. The tap then releases a water mist coupled with the gust. 

The team tested the device by conducting chromogenic reaction and residual bacteria experiments, which proved that the results of hand-washing with air can be similar to those of washing with water. 

In September 2015, the team took its invention to the Global Grand Challenges Summit. They took home the top award, beating teams from 14 universities including MIT and Cambridge. 

Now they have launched a second generation of their product, which is powered by electricity and equipped with an infrared ray induction system. 

The R&D team show their "air hand-washing device" at the 44th Geneva International Exhibition of Inventions in April 2016.