An IEEE Spectrum report and University of Michigan report tell of a fascinating advance in the development of a tiny microchip that can be implanted into the eye or other parts of the human body. The Phoenix microchip created my Michigan researchers would only require 1/30,000 as much power as comparable chips and would contain a sensor and a cpu enclosed in a 1 cubic millimeter package.
With such a low power microchip it would be feasible to run the chip for up to a year using current thin-film batteries. Countless applications for implants into the eye and other parts of the body would finally become feasible with a microchip that could operate on a battery for such an extended period.
Some cool quotes from the University of Michigan article:
The chip consumes just 30 picowatts during sleep mode. A picowatt is one-trillionth of a watt. Theoretically, the energy stored in a watch battery would be enough to run the Phoenix for 263 years.
Low power consumption allows us to reduce battery size and thereby overall system size. Our system, including the battery, is projected to be 1,000 times smaller than the smallest known sensing system today,” Blaauw said. “It could allow for a host of new sensor applications.
The microchip relies on a number of clever ideas to achieve its amazingly small power consumption. Chief among them is that unlike normal chips, this chip does not leak power when it is in idle mode (the period when it is not running instructions) which happens to be about 99% of the device’s lifetime. Essentially, the chip needs to turn on for a second or two and take a reading, then turn off for perhaps ten minutes before taking another reading. Another energy saving trick was to use a lower voltage, which causes the chip to run slower but in exchange causes it to use significantly less energy. From the IEEE article we see a number of other enhancements quoted here:
Phoenix makes use of some other power-saving tricks. It uses a very slow timer to tell the chip when to switch back on and take a new sensor reading. Phoenix’s timer operates at a frequency of less than one oscillation per second, drawing just 2 pW. The researchers also developed techniques for streamlining the set of instructions the processor must be able to execute and for compressing data in the chip’s memory. With fewer instructions and less data to store, the chip requires less memory, and because the volatile memory embedded in microprocessors always requires power to retain its contents, keeping the total amount of memory down is important.
