University of Michigan announces world's smallest computer
University of Michigan has produced a temperature sensing computer that measures 0.04 cubic millimeters, about a tenth the size of IBM's former record-setter. It's so small that one grain of rice seems huge in comparison and it's so sensitive that its transmission LED could trigger currents in its circuits.
The new device is a square with sides measuring just 0.3 mm each, making it about a tenth of the size of the previous world's smallest computer, a sand grain sized device that IBM unveiled back in March. The tiny device is a processor, RAM, a photovoltaic power system, a wireless transmitter and receiver that communicates using pulses of light. A base station beams light to the chip to power it, and the chip sends data back to base as light using a transmission LED. It might sound like a recipe for disaster to use light as both power and data, but the computer has been designed around that problem, with the team using switched capacitors instead of light-sensitive diodes. The small computer is designed to be used as a precision temperature sensor, able to monitor temperatures and changes in regions as small as a few cells, precise to about 0.1 C. It does so by converting temperatures into time intervals, and comparing that to a steady time interval transmitted to the chip by the base station.
The size forced researchers to get creative to reduce the effect of light. Researchers switched from diodes to switched capacitors, and had to fight the relative increase in electrical noise that comes from running on a device that uses so little power. The result is a sensor that can measure changes in extremely small regions, like a group of cells in your body. Scientists suspects that tumors are slightly hotter than healthy tissue, but it's been difficult to verify this until now. The tiny device could both check this claim and, if it proves true, gauge the effectiveness of cancer treatments. The team also envisions this helping to diagnose glaucoma from inside the eye, monitor biochemical processes and even study tiny snails. Since the temperature sensor is small and biocompatible, it can be implanted into a mouse and cancer cells grow around it. Researchers are using this temperature sensor to investigate variations in temperature within a tumor versus normal tissue and if we can use changes in temperature to determine success or failure of therapy.
The tiny size is leading the University of Michigan to question what a computer is. This does have a full fledged processor based on an ARM Cortex-M0+ design, but it loses all data when it loses power, just like IBM's device. That might be a deal breaker for people who expect a computer to be more complete. Still, this pushes the limits of computing power and suggests that nearly invisible computing may be relatively commonplace before long.