Small Scale Acoustic System Listens to Motion at Cellular Scale

The BBC is reporting on a project between Glasgow University, Oxford and Britain’s National Institute of Medical Research to develop a method of listening to the motion of microorganisms like bacteria. The researchers liken the new laser assisted acoustic monitoring system to its optical counterpart, the microscope.
From the BBC:

The micro-ear is based upon modifying an established technology that uses laser light to create so-called optical tweezers.These are already used to accurately measure tiny forces.
They work by suspending very small glass or plastic beads in a beam of laser light. Measuring the movement of these beads as they are jostled by tiny objects allows measurements of tiny forces that operate at molecular scales.
While many researchers use single beams of laser light to trap single beads, the micro-ear team hopes to use several arranged in a ring that will be able to surround and “listen to” an object of interest.
“We can look at a number of objects and watch them wobble,” said Prof Miles Padgett. “A wobbling object is like a diaphragm on a microphone.”
As such, said Professor Padgett, the wobble can be measured and used to turn the wobbles in the fluid surrounding the subject into sound giving an ear to events on the tiniest of scales.
By surrounding an object, said Professor Padgett, it should be easier to work out whether what that object does is the result of its own actions or something else.
A high-speed camera watches the motion of the ring of beads to determine the source of the motion.
Already the team has been able to listen to Brownian motion – the restless jostling of the atoms and molecules in a fluid.
Once the device is completed, a team led by Dr Richard Berry, a physicist at the University of Oxford, plans to use it to eavesdrop on flagella – the tiny motor that many bacteria such as E. coli use to move themselves around.

This is what Brownian motion sounds like: