An efficient new chip could be used for implantable medical sensors
Source: “The Phoenix Processor: a 30pW Platform for Sensor Applications”
Mingoo Seok et al.
IEEE Symposium on VLSI Circuits, June 2008
Results: Researchers at the University of Michigan have designed a chip less than one millimeter square that uses about a 10th as much energy as the most energy-efficient chips on the market.
Why it matters: The chip could be a boon to sensor design. Its small size–along with the energy savings it provides, which reduce the size of the battery needed–makes it feasible to build sensors that could be implanted under the skin to gauge glucose levels in subcutaneous fluid, or in contact lenses to monitor pressure on the eye.
Methods: Since sensor chips are inactive most of the time, the researchers focused on reducing the amount of energy wasted when the chip is in sleep mode. They redesigned the chip to use less memory (a big source of energy leakage), in part by incorporating hardware for data compression. Next, they reduced the small amounts of power that most transistors leak even when turned off, opting for slightly larger transistors that leak less. They also added special transistors that completely shut off the power supply to the processing transistors when they’re not in use.
Next Steps: The researchers will add a battery to the chip and develop a way to wirelessly download data from it.