Micromotes 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
Micromotes are 1 cubic millimeter general-purpose heterogeneous sensor node platform with a stackable multi-layer structure that includes a new, ultra-low power I2C (Inter-Integrated Circuit) interface for inter-layer communication. The system has an ultra-low power optical wakeup receiver, GOC (Global Optical Communication), which allows for re-programming or synchronization. It also includes an ultra-low power PMU (Power Management Unit) with BOD (Brown-Out Detector) to prevent processor malfunctions and battery damage, and also controls POR (Power-On Reset) modules in other layers to enable a proper reset sequence. Image and temperature sensors are implemented, but the modularity of the system allows end users to easily replace or add layers to incorporate specific circuits in appropriate technologies as needed.
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 For example, in as-yet-unpublished research, the Michigan team has implanted a Micro Mote inside a mouse tumour so that it can report back on its growth.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.