Computers no bigger than a snowflake

Tiny prototype computers, nicknamed 'smart dust', will be as small as a snowflake.

This next generation of computers is being developed at the University of Michigan in Ann Arbor. Only a cubic millimetre in size,  the first prototypes - dubbed Michigan Micro Motes - will have tiny Central Processor Units (CPUs) and sensors to monitor temperature or movement.

The 'smart dust' can send data via radio waves and will be able to run programs on a skeleton operating system whilst accessing equally small banks of RAM and flash memory.

There's no need for batteries to power the tiny machines - the motes are capable of scavenging energy from their surroundings. If a mote is near a source of light, it can even use a tiny solar panel.

Because they're so small, the nano-computers can be embedded in buildings and objects to provide constant updates on the surrounding environment.

There are potential medical benefits too.  Motes placed inside the body could monitor a patient's vital signs. In as-yet-unpublished research, the Michigan team has implanted a Micro Mote inside a mouse tumour so that it can report back on its growth.

Performing 100,000 operations on the mote's CPU using the same energy is feasible but the challenge remains - how to transmit more than one bit of information to the outside world.