Indian Origin Scientist Has Made a Major Breakthrough in Nanotechnology

by Hannah Punitha on Nov 14 2008 1:07 PM

 Indian Origin Scientist Has Made a Major Breakthrough in Nanotechnology
An Indian origin physics professor at Clemson has made a major breakthrough in nanotechnology which may lead to nano-scale electromechanical sensors that can read and alert us to toxic chemicals or gases in the air.
In the research, Apparao Rao found that nano-scale cantilevers hold the potential to detect the toxic chemicals or gases in the air.

He claimed that, when put into a small handheld device, the cantilevers can pave the way for real-time chemical alerts in battle, in industry, in health care and even at home.

"The ability to build extremely small devices to do this work has been something we've only seen so far in science-fiction movies," said Rao.

The micro- and nano-scale cantilevers, with the width of a human hair or smaller, look like tiny diving boards under an electron microscope.

The researchers have advanced the method of oscillating cantilevers that vibrate much like a guitar string and measure amplitude and frequency under different conditions, creating highly reliable sensors that can relay a message that there's trouble in the air.

"The current way of sensing involves an optical method that uses a relatively bulky and expensive laser beam that doesn't translate well to use in nano-scale cantilevers. Our method is fully electrical and uses a small AC voltage to vibrate the cantilever and simple electronics to detect any changes in the vibration caused by gaseous chemical or biological agents. This method enables the development of handheld devices that would beep or flash as they read gas and chemical levels on site," said Rao.

He said that the electromechanical sensors have varied applications- besides simultaneously reading multiple kinds of toxins in the environment, they can measure changes in humidity and temperature.

On the basis of preliminary results, it was found that the fully electrical sensing scheme is so sensitive that it can differentiate between hydrogen and deuterium gas, very similar isotopes of the same element.

And as the process is fully electrical, the size limitations that plague competing detection methods are not a problem here.

It is possible to make the cantilevers shrink down to the nano-scale and the operating electronics can be contained on a single tiny chip. Rao's research has shown that a single carbon nanotube can be used as a vibrating cantilever.

Rao applauded Clemson Professor Emeritus of Physics Malcolm Skove, of discovering that measuring the resonant frequency of a cantilever at the second or higher harmonies would get rid of the so-called parasitic capacitance, an unwanted background that obscures the signal and has been a major stumbling block to the advancement of similar technology.

"When we operate at these higher harmonics of the resonant frequency, we get extremely clean signals. It makes a tremendous difference, and the National Institute for Standards and Technology is interested in promoting the Clemson method as one of the standard methods for measuring the stiffness of cantilevered beams," said Rao.


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