Aalto scientists make a splash with water-based computer

Scientists at Aalto University, Finland, have made an eyebrow-raising computing breakthrough, creating digital bits from droplets of water.

According to researchers at Aalto University in Finland, water based computers could one day be used as part of lab on a chip devices.

In a recent study, the team found that water droplets would rebound off each other like billiard balls when placed on a highly water-repellent superhydrophobic surface, made of copper coated with silver, and chemically modified.

This means that a water droplet a few millimetres wide could be pushed down a slightly tilted track by another droplet, in the manner of electrons flowing down a traditional circuit.

One of the researchers, Dr Robin Ras, told TechEye that it was then possible to build basic memory devices, with droplets acting as a bit of digital information.  Each time a droplet was sent down the track it would push a stationary droplet, positioned in one of two parallel grooves in the track, into one of two pathways.  This would alternate for each droplet. 

By constructing a number of these devices Ras said it was possible to build memory devices, and could form the basis for simple computers.

“These logic systems are very interesting,” Ras said, speaking with TechEye.  “We have now demonstrated several logic gates that could operate using simply water.In principle these logic gates are also building blocks of computers”.  

The logic system may have novelty value, but Ras contends that there are potential uses for computing without the need for electricity, such as for lab on a chip devices. However, he admits that the likes of Intel have little to worry about in terms of speed, but they have other applications.

“The logic gate that we have developed will never compete in speed with silicon based logic systems,” Ras said, “but they can be useful in other systems.”

“Now we have the first demonstration where we can combine chemistry with such logic systems, because we compute with water droplets, and not with electrons,” he said, though he did highlight that commercial applications are some way off.

According to Ras, for some simple logic systems you would not need a silicon based computer, meaning that the water-based system developed at Aalto could be combined with microfluidic systems.

“We think that the applications are related to diagnostics, combining chemistry with analysis, such as lab on a chip devices,” Ras said.

Ras told us the next steps are to put individual logic gates in place after each other, so that multiple logic gates of memory can be put “in a series”, like in a silicon chip.