We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Intelligent Machines

From the Labs: Information Technology

New publications, experiments and breakthroughs in information technology–and what they mean.

Power Walking
Knee brace collects energy from its user’s stride.

The biomechanical energy harvester comprises an aluminum chassis and generator mounted on a customized orthopedic knee brace.

Source: “Biomechanical Energy Harvesting: Generating Electricity during Walking with Minimal User Effort”
Max Donelan et al.
Science 319: 807-810

This story is part of our May/June 2008 Issue
See the rest of the issue

Results: Scientists at Simon Fraser University in British Columbia have designed a knee brace that can harvest as much as 13 watts of power from the energy of its wearer’s strides, enough to charge 30 phones simultaneously.

Why it matters: With the proliferation of small gadgets that need to be charged, engineers are looking for alternatives to electrical outlets for charging. Researchers had already made shoe-­embedded generators that are easy to use, but they don’t collect more than a watt of power, making them impractical.

Methods: The researchers looked at the biomechanics of the human gait and saw that at the end of a stride, a person must actually exert energy to slow his or her moving leg. When the brace’s generator is engaged, it helps slow the leg for the wearer, capturing energy in much the same way that a hybrid car harvests power from braking.

Rather than forcing the wearer to work harder to produce extra energy, the brace reduces the effort exerted at the end of a stride. A sensor in the device monitors the angle of the knee to turn the generator on and off so that it doesn’t impede motion in the early part of a stride, when the knee is accelerating.

Next steps: The prototype device weighs just over three pounds; a spinoff company, Bionic Power, is developing a lightweight model.

Better Phase-Change Memory
Improved technology could compete with flash

Source: “A Multi-Level-Cell Bipolar-Selected Phase-Change Memory”
Ferdinando Bedeschi et al.
International Solid-State Circuits Conference, February 3-7, 2008, San Francisco

Results: Researchers at Intel and STMicroelectronics have developed an algorithm that doubles the amount of data that can be stored in a single phase-change memory cell, which represents bits as distinct arrangements of a material’s atoms.

Why it matters: For the past decade, flash memory has pro­vided compact, sturdy storage for small devices such as iPods and cell phones. But flash chips, which store data as electric charge, may soon reach the limits of their capaci­ty. Phase-change memory is among the alternatives that engineers have been pursuing. Previously, a phase-change memory cell could represent only one bit of data at a time. But the researchers found a way to store two bits in each cell, doubling the capacity of phase-change memory and making it competitive with flash.

Methods: A typical phase-change memory cell uses a type of glass that can switch back and forth between amorphous and crystalline states; the crystalline state represents a 1, the amorphous state a 0. The researchers created two-bit memory cells by giving the glass two more states in between amorphous and crystalline. To write data to a memory cell, an electrode heats it until a crystalline filament forms in the amorphous material. The bigger the filament grows, the more current passes through the memory cell. In the amorphous state, the memory cell represents two 0s. In the semi­amorphous state, it represents a 0 and a 1. In the semicrystalline state, it represents a 1 and a 0. In the crystalline state, with memory cell resistance at its lowest point, it represents two 1s.

Next steps: The phase-change chips were made using existing fabrication processes that yield memory cells larger than those of a flash memory chip. Future versions of phase-change memory should use newer processes that produce smaller cells, but researchers need to make sure that the technique holds up as the cell sizes shrink.

The AI revolution is here. Will you lead or follow?
Join us at EmTech Digital 2019.

Register now
More from Intelligent Machines

Artificial intelligence and robots are transforming how we work and live.

Want more award-winning journalism? Subscribe to Insider Plus.
  • Insider Plus {! insider.prices.plus !}*

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    Print + Digital Magazine (6 bi-monthly issues)

    Unlimited online access including all articles, multimedia, and more

    The Download newsletter with top tech stories delivered daily to your inbox

    Technology Review PDF magazine archive, including articles, images, and covers dating back to 1899

    10% Discount to MIT Technology Review events and MIT Press

    Ad-free website experience

You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.