Scientists in Beijing have developed a device which moves water vertically upwards… with no extra energy input at all! We all know that water won’t flow uphill on its own and that a pump, pulley, Archimedes screw or some other method of introducing energy is needed to lift it. But for how much longer? Scientists have been able to combine two very simple ideas in order to lift water. The first: water repellent materials (excitingly known as “superhydrophobic materials”), the second: water’s own surface tension – surface tension is what causes water droplets to have their characteristic shape and allow insects to float on the surface of bodies of water.
What happens when they come together, and how does it work?
The following video shows the set up – two important things to note are that there is already water in the pipe, and that at the bottom of the pipe there is a layer of a “superhydrophobic” mesh, made from copper treated with alkaline solution.
The mesh holds the existing column of water up due to its water-repellent nature. But to actually move it upwards? Small droplets of water are introduced from underneath the mesh and are drawn upwards into the water column, merging with it. Now for the clever bit – as the droplet merges with the column, its surface tension is lost, leading to the release of energy. It’s this energy which replaces the conventional methods, propelling the water upwards.
How will it be used?
One tiny problem with this is that it’s… tiny. This method can only be used for a height of 1cm – the energy that held a tiny drop of water in a spherical shape is hugely outdone by gravity beyond this point! So unfortunately current opportunities for scaling it up are minimal. Luckily, that doesn’t mean it’s not useful! While it can’t provide irrigation and drinking water on an effective scale, it can save lives through use in “labs on a chip”: tiny devices which can be used to test drinking water and identify contaminants within it, along with a huge number of other uses. They go by the less catchy name of microfluidic devices and are generally small blocks with networks of tiny channels going through them – water behaves differently on a microscopic basis. There is potential for several biomedical tests to be carried out on each chip, and this method could be very appropriate considering they work using the behaviour of water on a small scale!