Dr John Sader, from the University of Melbourne, discovered a design flaw in a key component of the Atomic Force Microscope (AFM).
[He] used established mechanical principles to prove that the popular V-shaped cantilever inadvertently degrades the performance of the instrument, and delivers none of its intended benefits.
In atomic force microscopy, small cantilevers are used to profile surface topography and structure. Shortly after the invention of the Atomic Force Microscope (AFM), almost two decades ago, V-shaped cantilevers were introduced to minimise the effect of lateral forces on image quality, a problem faced by the original rectangular design. Sader's research reveals that this attempt to rectify the lateral force problem was based on a false assumption.
Instead of increasing the resistance to twisting, V-shaped microcantilevers actually maximise twist and degrade the performance of the instrument.
Here is a diagram of a current AFM.
Sader’s calculations establish that the simple cantilever design of a straight beam proposed for the original atomic force microscope (Physical Review Letters, 1986) offers greatly improved performance over the V-shape while facilitating calibration and measurement interpretation.
This finding may reshape the industry by proposing a single new standard and because the AFM "has been the instrument of choice for three dimensional measurements at the atomic scale, since its invention in 1986."
Sader’s research will be published in the April issue of Review of Scientific Instruments.
For more information about the AFM, please visit the "How AFM works" page.
Source: University of Melbourne, March 6, 2003
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