Using drums to sense light

University of Oregon develops graphene nanomechanical bolometer
University of Oregon researchers have developed a graphene nanomechanical bolometer that captures the vibrations of very thin drums that are caused by light. (University of Oregon)

Physicists at the University of Oregon have developed technology that reportedly can sense presence of light at any wavelength. The technology, developed at the University of Oregon’s Alemán Lab, is known as a “graphene nanomechanical bolometer.”

The mechanical method captures the vibrations of infinitesimally thin drums that are caused by light. The physicists obtain measurements by listening to the sound of the light absorbed by the drumhead.   

The way the technology works is similar to the effect of banging a drum on a hot day. As the instrument heats up under the sun, the drumhead membrane will expand and its pitch changes, emitting a different tone than it would at cooler temperatures.

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Light waves do the same thing to the mechanical bolometers. As light hits the device’s drumhead, the membrane heats up, expands, and the vibrational pitch changes. The physicists can track these pitch changes to measure how much light hits the device.

“This tool is the fastest and most sensitive in its class,” said Benjamín Alemán, a professor of physics and a member of the University of Oregon’s Center for Optical, Molecular, and Quantum Science, in an article appearing on the University of Oregon’s website.

“This is a very new way of detecting light,” added David Miller, a doctoral student in the Alemán Lab. “We’re using a purely mechanical method to turn light into sound. This has the advantage of being able to see a much broader range of light.”

Miller explained that conventional detectors are reliable at reading high-energy light, like visible light or X-rays, but less adept at measuring the longer wavelengths on the electromagnetic spectrum, including infrared and radio waves. The mechanical device allows physicists to detect light of nearly any wavelength, which could be especially useful in astronomical observations, thermal and medical body imaging, and viewing in the infrared region. 

The device is constructed with a thin sheet of atoms over a hole etched into a piece of silicon. Then, using a technique developed previously in the lab, scientists cut the sheet to resemble a tiny trampoline. The device is one-tenth the width of a human hair, while the material used for the trampoline is a single atom thick, about a million times thinner than that same strand of hair.

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