Nanopillars sense tiny mass
doi:10.1038/nindia.2009.280 Published online 28 August 2009
How does one measure a mass increase of a few millionth of a trillionth of a gram? Researchers have designed nano-sized carbon pillars that can sense such tiny masses accumulated during electron beam irradiation on nanostructures1.
Such mass accumulations, which take place during scanning, have significant effects on the physical properties of materials, especially those of nanodimensions.
Mass accumulation is as small as a few attograms (ag -- millionth of a trillionth of a gram) per second. Conventional measurement techniques cannot easily detect such a tiny mass. The researchers used naphthalene precursor gas to deposit carbon nanopillars on a disk shaped crystal, which vibrates in response to electron beam irradiation.
When the pillars were irradiated by focused electron beams at various energy and current variables, mass accumulated only at the tip without increasing the diameter of the whole pillar. "This can be used to monitor mass accumulation in a scanning electron microscope," says Vishwas N. Kulkarni, one of the researchers. If developed completely it would probably find applications in safety (for detection of explosive molecules) and space equipment, he adds.
- Banerjee, A. et al. The measurement of attogram mass accumulation on nanostructures during e-beam scanning, using carbon nanopillars in resonant mode. Nanotechnology. 20, 345501 (2009) | Article