Researchers in the US have unveiled the first computer to be built entirely from carbon nanotube (CNT) transistors. Their prototype is nothing fancy – or fast – in terms of computing power, but it can use a simple operating system to switch between two different tasks: counting and sorting numbers.

People have been making CNT transistors and circuits for over a decade, but using them to build complex electronic systems has proved tricky. Max Shulaker and his colleagues at Stanford University in the US have overcome many of the traditional difficulties associated with building CNT chips. They devised an algorithm to bypass CNTs that were not aligned parallel on the chip and also got rid of ‘metallic’ CNTs (which always conduct electricity rather than acting as semiconductors) by passing electricity through them until they vaporised. The resulting parallel semiconducting CNTs could then be made into functioning circuits.

It has long been predicted that CNT technology will one day overtake traditional silicon chips, which are reaching their limits in terms of miniaturisation. The development of a functional computer shows this is a real possibility, and the team are confident their prototype can be improved.