A decade in the making, but they’ve finally cracked it. You might not naturally pair computers with water—at least not in a positive way—but researchers at Stanford University have managed to create a computer that works using water droplets.

Normally, your computer transfers data around a circuit board using electrons. But scientists have managed to turn this on its head by making a computer in which the presence or absence of a water drop represents the ‘1’ or ‘0’ of binary code. The new computer is able to perform all the same processes of a normal computer, albeit much slower. However, the real advantage of this new tech is that those little water droplets could carry chemicals, making the computer a complex delivery system.  

“We already have digital computers to process information. Our goal is not to compete with electronic computers or to operate word processors on this,” explained Manu Prakash, who has been developing this idea for the past 10 years. “Our goal is to build a completely new class of computers that can precisely control and manipulate physical matter. Imagine if when you run a set of computations that not only information is processed but physical matter is algorithmically manipulated as well. We have just made this possible at the mesoscale.”

Credit: Stanford University

How it works is quite complicated, so bear with me here. The engineers needed to develop a clock that would work for a fluid-based computer. Clocks are essential for a computer to function correctly, because as programs complete several operations, they all need to start and stop at the same time. If they don’t, everything falls out of synch and the whole thing falls apart.

The researchers managed to solve this by using a rotating magnetic field. They then built a miniature array of iron bars on which the water, which is infused with magnetic nanoparticles, could run. When they turned the magnet on, every time it rotated, the field flipped and the polarity of the bars reversed. The pattern in which they put the iron bars altered the shape of the magnetic field generated by the magnet. This meant that the magnetic water droplets could be moved in a predetermined direction, and thus the scientists where able to control where to put the ‘information.’

“Following these rules, we've demonstrated that we can make all the universal logic gates used in electronics, simply by changing the layout of the bars on the chip,” said Georgios Katsikis, first author on the paper. “The actual design space in our platform is incredibly rich. Give us any Boolean logic circuit in the world, and we can build it with these little magnetic droplets moving around.”

Currently, each drop of water is about the size of a poppy seed, and the chip of iron bars is only the size of half a postage stamp. But the researchers hope to try and make it smaller so that it can complete more operations per time. They think that their work could be used to run reactions, where instead of them happening in a test tube, they occur in the little drops of water.