Tuesday, July 29, 2008

My Gold Atom Weighs More Than Yours

Researchers at UC Berkley and Berkley Lab have developed a scale sensitive enough to measure, at room temperature, the mass of a single atom of gold, in a little over a second of time.

Although scientists can already measure the mass of a single atom using mass spectrometry, this new method is based on nanoelectromechanical (NEMS) technology, making it more sensitive and compact. So small is the sensor, researchers say it could eventually be put on a chip.

The mass sensor is made of a single carbon nanotube enclosed in two walls to increase rigidity and ensure uniform electrical properties, one end of the nanotube waves freely while the other is connected to an electrode near a counter electrode.

Appyling a DC voltage source allows researchers to create a negative electrical charge on the free end of the carbon nanotube, making it vibrate with a specific resonance frequency. Subsequently, the device works by measuring the change in resonance frequency of the carbon nanotube under the weight of the molecule or atom.

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