Posts Tagged ‘NIST’
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August 17th, 2009
Size matters in the nanoworld
As you will know, the smaller something gets the harder it becomes to measure. We can deal with measuring the length of a grain of rice, say, with a ruler and a bit of patience. If we then wanted to measure the width of a grain of sand, a well-calibrated light microscope would make this a straightforward task. However, as we shrink further still the physics of light itself starts conspiring against us, making increasingly complex pieces of equipment necessary to give us our desired measurements.So, how do we go about accurately measuring the size of nanoparticles? Their name alone gives a clue that this is no facile task. Various specialised microscopes can be used (for examples see here and here), but these techniques only allow the analysis of a relatively limited sample size. They can’t deliver a figure for, say, a suspension of nanoparticles sat in a round-bottomed flask. You may ask why this is important… Well, cells are known to respond very differently to the presense of nanoparticulates of different sizes, so having this information is very important indeed.
With these issues in mind, an ASTM & NIST organised multi-laboratory assessment has recently been completed, resulting in the generation of the ASTM standard E2490 - a comprehensive guide for the measurement of particle size distribution of nanomaterials in suspension by Photon Correlation Spectroscopy (PCS). PCS (also known in some circles as Dynamic Light Scattering) is a powerful technique which allows accurate calculations of size in response to the scattering of laser light shone through a suspension. The maths is complex, as are the system variables involved, precisely why this is an important document. The NIST also supply certified solutions of gold nanoparticles of three different diameters, allowing organisations to accurately calibrate instrumentation.
Having nanoparticles of a precise size is becoming increasingly important in fields such as medicine, so the teams involved in the collation of this data should be congratulated for making the measurement of such particles that little bit easier…
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June 25th, 2009
Supporting the gold team
Will gold retain the cup at the forthcoming RoboCup?
Since 1997, RoboCup has been leading the way in research about robotics and artificial intelligence. In 2007, the US standard’s body NIST conducted a nano-football competition and demonstration in conjunction with RoboCup. NIST’s goal in coordinating a competition between the world’s smallest robots was to show the feasibility and accessibility of technologies for fabricating MicroElectroMechanical Systems (MEMS) devices.
The devices were operated by remote control under an optical microscope and moved in response to changing magnetic fields or electrical signals transmitted across the microchip arena. They were considered “nanoscale” because their masses range from a few nanograms to a few hundred nanograms. The winner of the 2007 event was ETH Zurich whose ‘robot’ consisted of two small pieces of soft magnetic separated by a gold spring and base frame.
magnetic materials on the gold base
In a few weeks it will be the 2009 event - will a gold ‘player’ lift the cup again?!
Trevor Keel
Richard Holliday
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