Researchers create computer that fits on a pen tip

Micro-computer's first use will be for medical monitoring

Researchers at the University of Michigan today announced that they have created the first prototype for a millimeter-scale computing system.

The computer, called the Phoenix chip, is about one cubic millimeter in size and was designed to be implanted in the human eye to monitor the intraocular pressure of glaucoma patients. It can hold up to a week's worth of data.

"This is the first true millimeter-scale complete computing system," researcher Dennis Sylvester, a professor in the university's College of Engineering and Computer Science, said in a statement.

Within the computer is an ultra-low-power microprocessor, a pressure sensor, memory, a thin-film battery, a solar cell and a wireless radio with an antenna that can transmit data to an external reader device held near the eye.

Text about this image

The Phoenix chip computer just covers the letter N on a penny

Click to view larger image.

The chip sips power. It has a power-gating architecture with an extreme sleep mode that wakes the computer up briefly every 15 minutes to take readings, and it uses an average of just 5.3 nanowatts each time it turns on.

The Phoenix chip has photovoltaic charging system that requires 10 hours of indoor light or 1.5 hours of sunlight to fully charge the battery.

The chip's micro radio automatically tunes into whatever wireless frequency is available in order to download data to a reader. The data can then be used as part of an electronic medical record for treatment.

According to researchers, the micro computers and their wireless networks could one day also be used to track pollution, monitor structural integrity, perform surveillance, or make virtually any object smart and trackable. "Our work is unique in the sense that we're thinking about complete systems in which all the components are low-power and fit on the chip," Sylvester said. "We can collect data, store it and transmit it. The applications for systems of this size are endless."

The researchers presented papers on the new microcomputers and the networks at the International Solid-State Circuits Conference (ISSCC) in San Francisco. The work is being led by Sylvester and two other faculty members in the University of Michigan Department of Electrical Engineering and Computer Science: professor David Blaauw and assistant professor David Wentzloff

Blaauw said that once chips reach the nanoscale level, hundreds of the computers could be fitted onto a single silicon wafer to perform multiple monitoring tasks.

The researchers pointed to Bell's Law, which states that there's a new class of smaller, cheaper computers about every decade. With each new class, the volume shrinks by two orders of magnitude and the number of systems per person increases. The law has held true from the mainframes of the 1960s through the personal computers of the '80s, the notebooks of the '90s and the today's smart phones, they said.

"When you get smaller-than-handheld devices, you turn to these monitoring devices," Blaauw said in a statement. "The next big challenge is to achieve millimeter-scale systems, which have a host of new applications for monitoring our bodies, our environment and our buildings."

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian, or subscribe to Lucas's RSS feed . His e-mail address is

Copyright © 2011 IDG Communications, Inc.

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