A new chip uses so little power, it could enable sensors, communication devices and other gadgets that run on body heat and movement alone.
The chip uses 70 percent less voltage than current chip technologies. It could lead to an order-of-magnitude increase in energy efficiency for electronics in the next five years, said the MIT researchers who developed the new technology.
"It will extend the battery lifetime of portable devices in areas like medical electronics," said Anantha Chandrakasan, a professor of electrical engineering at MIT. "When you look at the digital processor, the fact is that we may be able to reduce the energy needed by 10 times."
Better circuit design and batteries have already led to smaller, more-mobile electronics. But changing a battery is not an option for many medical and military devices. Military researchers at Darpa, which helped fund the MIT work, are keen to increase the lifespan of these technologies or even eliminate the need to charge them. Military strategists imagine these types of low-power chips could be used in the battlefield, particularly in body and environmental sensors. Among more mundane uses, Nokia is looking at low-voltage chips for use in cellphones and computers. Intel also has a low-power-chip research unit.
Designing a low-voltage chip is complicated, because transistors – the bases of chips – use voltage changes to switch on and off. Increase the voltage to the system, and the transistor eventually hits its threshold and switches on. Decrease it, and the transistor switches off. That ability is what allows it to store the binary information – the 1's and 0's – that forms the basis of computing.
But at low voltages, variations introduced during transistor production can cause errors.
"When you scale voltages, the first thing to break is memory on a chip," Chandrakasan said. "You have to redesign the memory and logic so you can handle the variation."
Working with scalable energy voltages, he said, required a whole suite of design techniques, including a fundamental change in the memory cell from six transistors to eight.
The researchers think medical devices like pacemakers and various military applications could use the new chip within five years.
Decreasing power consumption is the key to unleashing medical technologies on the battlefield, said Barry Perlman, associate director for technology at the Army's Communications Electronics Research and Development Center at Fort Monmouth, New Jersey.
"Sensors that are involved in monitoring the soldier's health, managing blood flow or heart rate, or measuring the thermal profile of the soldier – there's no question all of this is very, very important," Perlman said. "But it's not realistic unless the power requirement associated with them is really low."
The power requirements for sensors attached to the body could be reduced to near zero, Chandrakasan said. The body's heat and movement could generate the microwattage necessary to power the devices.
MIT graduate student Joyce Kwong will discuss the new chip at the International Solid-State Circuits Conference in San Francisco on Tuesday. The researchers designed their proof-of-concept chip with researchers at Texas Instruments, using a standard semiconductor-fabrication process.
The major trade-off for the lower power usage is raw speed, said Connie Brown, spokeswoman for Intel's mobile platforms. Intel's newest mobile platform, SilverThorne, cuts power consumption to less than 2 watts. That's less than one-fifth of any previous offerings and one-eighth the power draw of ballyhooed products like the MacBook Air's new chip, which draws 17 watts. The MIT team's chip uses between 1 and 100 microwatts.
While a couple of watts in energy savings might not be a big deal to consumers with access to the power grid, Perlman said soldiers often have to carry all the power for their battlefield communications devices – which are about 10 times bigger than typical cellphones.
"You can start to imagine how power becomes a very, very important parameter to the soldier," he said.