Publication in Nature Photonics – Bacterium in a Laser Trap

Freiburg Researchers develop a light tube that can grab and scan even the tiniest of unicellular organisms



With the optical tweezers, a laser beam holds a bacterium in place and records its movements in detail. In the background is an image taken with a conventional microscope in which it is only possible to make out the bare outline of the bacterium.

Scientists from the Department of Microsystems Engineering (IMTEK) of the University of Freiburg have constructed an innovative new optical trap that can grab and scan tiny elongated bacteria with the help of a laser. The physicists Prof. Dr. Alexander Rohrbach und Matthias Koch created a kind of light tube that traps the agile unicellular organisms. Optical tweezers could previously only be used to grab bacteria at one point, not to manipulate their orientation. The Freiburg researchers have now succeeded in using a quickly moving, focused laser beam to exert an equally distributed force over the entire bacterium, which constantly changes its complex form. At the same time, they were able to record the movements of the trapped bacterium in high-speed three-dimensional images by measuring miniscule deflections of the light particles. The team reports their findings in the current online edition of Nature Photonics.

Read more:   >>> Press Release by the University of Freiburg

Original publication:    >>> M. Koch, A. Rohrbach. Object-adapted optical trapping and shape-tracking of energy-switching helical bacteria. Nature Photonics, 2012


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