In 2015, the Michigan Micro Mote constituted the first complete, operational computer system measuring as small as two millimeters across. “To be “complete,” a computer system must have an input of data, the ability to process that data – meaning process and store it, make decisions about what to do next – and ultimately, the ability to output the data.” Prof. Blaauw explained. “The sensors are the input and the radios are the output. The other key to being a complete computer is the ability to supply its own power.”
In 2017, the systems are one cubic millimeter. There are several types and are a line of the world’s smallest computers. They have one megabyte of flash memory. Their broader goal is to make smarter, smaller sensors for medical devices and the internet of things—sensors that can do more with less energy. Many of the microphones, cameras, and other sensors that make up eyes and ears of smart devices are always on alert, and frequently beam personal data into the cloud because they can’t analyze it themselves. Some have predicted that by 2035, there will be 1 trillion such devices. “If you’ve got a trillion devices producing readings constantly, we’re going to drown in data,” says Blaauw. By developing tiny, energy efficient computing sensors that can do analysis on board, Blaauw and Sylvester hope to make these devices more secure, while also saving energy.
Micro mote designs now use only a few nanowatts of power to perform tasks such as distinguish the sound of a passing car and measuring temperature and light levels. They showed off a compact radio that can send data from the small computers to receivers 20 meters away—a considerable boost compared to the 50 centimeter range they reported last year at ISSCC
Another micro mote they presented at the ISSCC incorporates a deep-learning processor that can operate a neural network while using just 288 microwatts. Neural networks are artificial intelligence algorithms that perform well at tasks such as face and voice recognition. They typically demand both large memory banks and intense processing power, and so they’re usually run on banks of servers often powered by advanced GPUs.
The Michigan Micro Mote contains solar cells that power the battery with ambient light, including indoor rooms with no natural sunlight, allowing the computers to run perpetually.
This line of “smart dust” devices includes computers equipped with imagers (with motion detection), temperature sensors, and pressure sensors. They are the culmination of work initiated by Blaauw and Sylvester on very low-power processing for millimeter-scale systems.
Photo: University of Michigan and TSMC One of several varieties of University of Michigan micro motes. This one incorporates 1 megabyte of flash memory. Previous versions of the micro motes used 8 kilobytes of SRAM
An Astonishing Lack of Power
A key breakthrough in the size/power matchup came with the Phoenix processor in 2008. The Phoenix processor is miniscule at 915 x 915µm2, and boasts ultra-low operating voltage and a unique standby mode that results in an average power consumption of only 500pW. (Consider that 1pW is the average power consumption of a single human cell.)