"World's smallest wrench" is able to rotate individual cells
By Ben Coxworth
December 4, 2012
If you were a scientist looking at a cell with a microscope, what would you do if you wanted get a look at the far side of that cell? You could try reaching in with a very fine-tipped pair of tweezers, but ... you’d probably be better off using something known as a fiber-optic spanner.
A team from the University of Texas at Arlington, led by assistant professor Samarendra Mohanty, created the device.
The business end of the fiber-optic spanner consists of two optical fibers, which are situated end-to-end with a small gap between them. A beam of laser light is emitted from each of these fibers – when the two beams are lined up, the force of the streaming photons is sufficient to trap a microscopic object such as a cell between them. If the fibers are slightly offset, however, and their beams hit that cell on either side, they can actually spin it around in place.
By changing the orientation of the fibers, the cell can be turned on any axis. It’s similar to the technology used in “optical tweezers,” although those are used more just for pushing or holding microscopic objects, not for rotating them.
Along with its use for examining cells, the researchers believe that the fiber-optic spanner could also be used for applications such as untwisting DNA strands, guiding neurons within the spinal cord, or mixing fluids in lab-on-a-chip devices.
A paper on the research was recently published in the journal Optics Letters.
Source: The Optical Society