Researchers unveil first mm-scale computing system

Researchers at the International Solid-State Circuits Conference in San Francisco demonstrate a prototype implantable eye pressure monitor and a tiny new radio.

Elizabeth Armstrong Moore
Elizabeth Armstrong Moore is based in Portland, Oregon, and has written for Wired, The Christian Science Monitor, and public radio. Her semi-obscure hobbies include climbing, billiards, board games that take up a lot of space, and piano.
Elizabeth Armstrong Moore
2 min read

University of Michigan computer scientists and engineers are at the International Solid-State Circuits Conference in San Francisco today presenting papers on two systems: a prototype implantable eye pressure monitor for glaucoma patients and a compact radio for wireless sensor networks.

This prototype implantable eye pressure monitor is 1 cubic millimeter. Greg Chen

What makes their presentation so remarkable is that both systems involve what is believed to be the first complete millimeter-scale computing system.

The near-invisible package is just over 1 cubic millimeter in size and includes an ultra-low-power microprocessor, a thin-film battery, a solar cell, memory, a pressure sensor, and a wireless radio with an antenna.

"Millimeter-scale systems...have a host of new applications for monitoring our bodies, our environment, and our buildings," said Professor David Blaauw in a news release. "Because they're so small, you could manufacture hundreds of thousands on one wafer. There could be 10s to 100s of them per person, and it's this per capita increase that fuels the semiconductor industry's growth."

The team points to Bell's Law, formulated by computer engineer Gordon Bell in 1972, which says that a new class of smaller and cheaper computers is developed roughly every decade. This is considered to be a partial corollary to Moore's Law, established in 1970 and named after Intel co-founder Gordon Moore (first names coincidental), which describes the now 50-plus-year trend that the number of transistors able to be placed on an integrated circuit doubles every two years.

The new system out of Michigan is being hailed as the first in a new class of millimeter-scale computing, and while the researchers are specifically targeting the medical side of body sensor networks, other potential applications include tracking such things as pollution, weapons, structural integrity, and more.

The eye pressure monitor is designed not only for direct implantation but also continuous tracking of glaucoma, a disease that can lead to blindness. It incorporates the team's third-gen Phoenix Processor, which combines an extreme sleep mode and a unique power-gating system for ultra-low-power usage (averaging 5.3 nanowatts).

The system wakes every 15 minutes to take measurements and relies on 10 hours of indoor light or 1.5 hours of sunlight every day for full battery recharging. The team says the device could be commercially available in the next several years.

The researchers are also working on a radio with an on-chip antenna using an advanced complementary metal-oxide-semiconductor (CMOS) process that allows them to control the antenna's shape and size, and thus its response to electrical signals. Because of this control, they can do away with the bulky external crystals that keep time and select radio frequency bands for communication between two isolated devices, thereby drastically reducing the size of the radio system.

The university hopes to patent these tiny-yet-huge developments, and is looking for commercial partners to help bring the tech to market.