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An alternative method to determining optical lever sensitivity in atomic force microscopy without tip-sample contact
Review of Scientific Instruments
  • Christopher J. Tourek, Iowa State University
  • Sriram Sundararajan, Iowa State University
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Force studies using atomic force microscopy generally require knowledge of the cantilever spring constants and the optical lever sensitivity. The traditional method of evaluating the optical lever sensitivity by pressing the tip against a hard surface can damage the tip, especially sharp ones. Here a method is shown to calculate the sensitivity without having to bring the tip into contact. Instead a sharpened tungsten wire is used to cause a point contact directly onto the cantilever and cause cantilever bending. Using beam theory, the sensitivity thus found can be converted to the equivalent sensitivity that would be obtained using the tip location. A comparison is presented between sensitivity values obtained from the conventional tip contact method and those derived from the wire-based technique for a range of cantilevers in air. It was found that the difference between the calculated sensitivity from the wire-based technique and the sensitivity obtained conventionally was less than 12%. These measurements indicate the presented method offers a simple alternative approach to obtain optical lever sensitivity without compromising the tip shape.

The following article appeared in Review of Scientific Instruments 81 (2010): 073711, doi:10.1063/1.3459886.

Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
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American Institute of Physics
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Christopher J. Tourek and Sriram Sundararajan. "An alternative method to determining optical lever sensitivity in atomic force microscopy without tip-sample contact" Review of Scientific Instruments Vol. 81 Iss. 7 (2010) p. 073711
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