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Scientists race to build smallest 'car'

From Indo-Asian News ServiceScientists at Rice University, Houston, have zoomed ahead in the race to build the smallest "car" - a very small moving object that has applications only at the molecular level.

india Updated: Oct 29, 2005 17:01 IST

Scientists at Rice University, Houston, have zoomed ahead in the race to build the smallest "car" - a very small moving object that has applications only at the molecular level.

The "nanocar" resembles the average automobile only in shape as it measures only three by four nanometres - so small that a million of them parked bumper to tail may just be barely visible to the naked eye.

A human hair, by comparison, is about 80,000 nanometres in diameter. The nanocar, however, has a rolling movement like a car.

The innovation is described in a research paper that is to appear in an upcoming issue of the journal Nano Letters.

"The synthesis and testing of nanocars and other molecular machines is providing critical insight in our investigations of bottom-up molecular manufacturing," said James M Tour, one of the two lead researchers.

"We'd eventually like to move objects and do work in a controlled fashion on the molecular scale, and these vehicles are great test beds for that. They're helping us learn the ground rules," a university press release quoted Tour as saying.

Other research groups have created nanoscale objects that are shaped like automobiles, but study co-author Kevin F. Kelly said Rice's vehicle is the first that actually functions like a car, rolling on four wheels in a direction perpendicular to its axles.

Kelly and his group, experts in scanning tunneling microscopy (STM), provided the measurements and experimental evidence that verified the rolling movement.

"It's fairly easy to build nanoscale objects that slide around on a surface," Kelly said. "Proving that we were rolling - not slipping and sliding - was one of the most difficult parts of this project."

To do that Kelly and graduate student Andrew Osgood measured the movement of the nanocars across a gold surface. To prove that the cars were rolling rather than sliding, Kelly and Osgood took STM images every minute and watched the cars progress.

Because nanocars' axles are slightly longer than the wheelbase - the distance between axles - they could determine the way the cars were oriented and whether they moved perpendicular to the axles.

The Rice team has already followed up the nanocar work by designing a light-driven nanocar and a nanotruck capable of carrying a payload.

First Published: Oct 29, 2005 17:01 IST