Noisy tweezers - David Bradburn
Think about designing a pair of tweezers that actually don't work by touch? Well this is exactly what a group of scientists from the United States have managed to do [Ding et al., PNAS (2012), doi:10.1073/pnas.1209288109]
The tweezers are sensitive enough to manipulate single particles and cells so will find valuable application in biology, chemistry, physics and materials science disciplines.
The full term given to their device is surface acoustic wave tweezers. Smaller than a US dime, the tweezers are based on a piezoelectric material that converts vibrations to standing surface acoustic waves or SAWS. The sample to be manipulated is held in a liquid which is then perturbed by the SAWS which create pressure fields through the liquid.
A more established technique called optical tweezers use a focused light to provide an attractive or repulsive force to hold and manipulate objects as small as single atoms. These particular tweezers have again found particular application in biological systems but this time they can work down to the nanoscale.
The beauty and potential of the acoustic tweezer however are those noninvasive beams that doctors use in studying developing embryos in the mothers uterus. Application so far has only been in manipulating and moving around small objects although by extending the frequency range the scientists should in theory be able to manipulate nanoscale objects, which will then allow them to go head to head with optical tweezer technology.
With further studies being conducted to assess the feasibility of creating compact noninvasive and inexpensive point-of-care applications this will be an interesting time to see or even hear just how far tweezers can go in manipulating smaller and smaller objects.
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Posted 05/07/2012 by Materials Today
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