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A Light-Driven Plasmonic Motor

Particle-size light mill could power nanomachines

2 min read

20 July 2010—For decades, scientists have known that photons possess enough linear and angular momentum to turn a pinwheel-shaped dielectric, so long as the pinwheel is the right size and light enough. Exactly how this works remains unclear, and so far these motors, called light mills, have been too weak to be useful outside the laboratory.

But a team of researchers at the University of California, Berkeley, has now developed a light-driven nanosize motor that addresses the limitations of earlier light mills. The new motor, made of gold, generates comparable torque, but it is much smaller. At 100 nanometers across (one-tenth the size of other motors) it would make possible things like unwinding DNA in living cells and nanoscale harvesting of solar energy, the scientists say. The work, which was funded by grants from the National Science Foundation and the U.S. Department of Energy, was reported 4 July in Nature Nanotechnology.

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The Transistor at 75

The past, present, and future of the modern world’s most important invention

2 min read
A photo of a birthday cake with 75 written on it.
Lisa Sheehan

Seventy-five years is a long time. It’s so long that most of us don’t remember a time before the transistor, and long enough for many engineers to have devoted entire careers to its use and development. In honor of this most important of technological achievements, this issue’s package of articles explores the transistor’s historical journey and potential future.

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