Micro-Ear’ Will Listen to Living Cells

A new development, the “micro-ear,” will soon be able to help scientists listen to the tiniest events, exactly as the microscope reveals those things that otherwise would appear to be invisible.

The device, under development by the National Institute of Medical Research at Mill Hill and the Universities of Glasgow and Oxford, is intended to give researchers an eye – or ear, rather – into the world of living cells.

The technology is based on one that is already in use as a form of optical tweezers that is created by using a laser to measure tiny glass or plastic beads in a beam of light as they are moved around by tiny objects. The movement of the beads allows the measurement of the tiny forces that operate at molecular scales – piconewton forces, they are called, a millionth of the force that a grain of salt exerts when resting on a table.

“We are now using the sensitivity afforded by the optical tweezer as a very sensitive microphone,” University of Glasgow’s Professor Jon Cooper, who heads the project, explained over the weekend to BBC. “The optical tweezer can measure or manipulate at piconewton forces.”

The micro-ear team plans to arrange several beams of light in a ring in order to surround and “listen to” an object of interest. A high-speed camera will also watch the motion of the ring of beads to determine its source, explained Professor Miles Padgett, a member of the research team. In addition, he said, “we can trap and hold the beads and connect the output to a speaker so we can hear them vibrating.”

So far, the team has been able to pick up the sound of Brownian motion – the movement of atoms and molecules in a fluid.

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