David Kirkpatrick

September 10, 2010

Single ions crossing a nano bridge

Filed under: Science — Tags: , , , , , — David Kirkpatrick @ 11:11 am

Don’t see any current practical applications — aside from desalination — on this right now (but now with a proof-of-concept I bet this’ll be leveraged in new research), but it is impressively cool.

From the link:

In the Sept. 10 issue of Science, MIT researchers report that charged molecules, such as the sodium and  that form when salt is dissolved in water, can not only flow rapidly through carbon nanotubes, but also can, under some conditions, do so one at a time, like people taking turns crossing a bridge. The research was led by associate professor Michael Strano.

The new system allows passage of much smaller molecules, over greater distances (up to half a millimeter), than any existing nanochannel. Currently, the most commonly studied nanochannel is a silicon nanopore, made by drilling a hole through a silicon membrane. However, these channels are much shorter than the new nanotube channels (the nanotubes are about 20,000 times longer), so they only permit passage of large molecules such as DNA or polymers — anything smaller would move too quickly to be detected.

Strano and his co-authors — recent PhD recipient Chang Young Lee, graduate student Wonjoon Choi and postdoctoral associate Jae-Hee Han — built their new nanochannel by growing a nanotube across a one-centimeter-by-one-centimeter plate, connecting two water reservoirs. Each reservoir contains an electrode, one positive and one negative. Because electricity can flow only if protons — positively charged , which make up the electric current — can travel from one electrode to the other, the researchers can easily determine whether  are traveling through the nanotube.

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