Nanoscale trampoline-like sensor measures light mechanically

October 29, 2019 //By Rich Pell
Trampoline-like sensor measures light mechanically
Researchers at the University of Oregon (Eugene, OR) have developed an ultrasensitive method to measure light using microscopic drums.

The technology, known as a "graphene nanomechanical bolometer," offers an alternative to the conventional way of using electricity to measure light - such as found in devices like a smartphone's camera - by leveraging a mechanical method and new material to detect nearly every color of light at high speeds and high temperatures. The tool, say the researchers, is the fastest and most sensitive in its class.

The new method captures the vibrations of infinitesimally thin drums that occur when they are hit by light. Measurements are obtained by listening to the sound of the light absorbed by the drumhead, an effect similar to that of banging a drum on a hot day - as the instrument heats up under the hot sun the drumhead membrane expands and its pitch changes, emitting a different tone than it would at cooler temperatures.

The same thing occurs with the mechanical bolometers: as the waves of light hits the device's drumhead, the membrane heats up, expands, and the vibrational pitch changes. The researchers can track these pitch changes to measure how much light hits the device.

"This is a very new way of detecting light," says David Miller, a doctoral student in the University's experimental physics 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."

While conventional detectors are very reliable at reading high-energy light, like visible light or X-rays, say the researchers, they are less adept at measuring the longer wavelengths on the electromagnetic spectrum, including infrared and radio waves. Their mechanical device fills that void and allows detection of light of nearly any wavelength, which could be especially useful in astronomical observations, thermal and medical body imaging, and seeing deep into the infrared.

The device was constructed by first stretching a thin sheet of graphene - which consists of a single layer of

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