Smart dust computers are no bigger than a snowflake

Thousands of tiny computers that scavenge power from their surroundings could one day be used to monitor your world

THOUGHT your smartphone or tablet packed a big punch for its size? Pah, that's nothing. The next generation of computers will be able to carry out complex calculations but will be little bigger than a snowflake.

Such tiny computers – nicknamed smart dust – would work much like their larger cousins, says Prabal Dutta at the University of Michigan in Ann Arbor. They will have tiny CPUs that run programs on a skeleton operating system and be able to access equally small banks of RAM and flash memory. The plan is for such sensor-packed machines to be embedded in buildings and objects in their hundreds or even thousands, providing constant updates on the world around us.

Dutta's group is creating the first prototypes, which they have dubbedMichigan Micro Motes. These devices, a cubic millimetre in size, come equipped with sensors to monitor temperature or movement, say, and can send data via radio waves.

But how do you charge something so small? "The vision of blanketing the world with smart sensors is very compelling," says Joshua Smith, head of the Sensor Systems Laboratory at the University of Washington in Seattle. "But a lot of sensor networks researchers found themselves surrounded by mountains of depleted batteries and dead sensor nodes."

So, like microscopic Robinson Crusoes, the motes will live off the power they can scavenge from their surroundings. A mote near a light source might use a tiny solar panel, while a mote running somewhere with greater temperature extremes can be built to tap into that, by converting the heat energy that flows between hot and cold into electricity.

So what will be smart dust's killer app? The Michigan team says Micro Motes could be used to monitor every tiny movement of large structures like bridges or skyscrapers. And motes in a smart house could report back on lighting, temperature, carbon monoxide levels and occupancy. With motes embedded in all of your belongings it might be possible to run a Google search in the physical world. For example, asking Google "where are my keys?" would give you the right answer if they have been fitted with a mote.

Smart dust computers could make efficient medical implants too. The idea is that motes placed inside the body would monitor a patient's vital signs. For example, in as-yet-unpublished research, the Michigan team has implanted a Micro Mote inside a mouse tumour so that it can report back on its growth.

Smith is also working on miniature computing, with his wireless identification and sensing platforms (WISPs). Further along in development than Micro Motes – albeit larger – WISPs communicate via radio frequency identification devices, using the same computer language that your next-generation credit card uses. Like Micro Motes, WISPs don't need batteries and only consume what they can scavenge – stray signals from a nearby TV tower might do the trick, for instance.

But communication remains a key bottleneck for the next wave of computer miniaturisation, says Dutta. For the same chunk of energy a mote could perform 100,000 operations on its CPU but only transmit one bit of information to the outside world, he says.