Interlaboratory round robin on cantilever calibration for AFM force spectroscopy

Joost te Riet, Allard J. Katan, Christian Rankl, Stefan W. Stahl, Arend M. van Buul, In Yee Phang, Alberto Gomez-Casado, Peter Schön, Jan W. Gerritsen, Alessandra Cambi, Alan E. Rowan, G. Julius Vancso, Pascal Jonkheijm, Jurriaan Huskens, Tjerk H. Oosterkamp, Hermann Gaub, Peter Hinterdorfer, Carl Figdor, Silvia Speller

Research output: Contribution to journalArticleAcademicpeer-review

86 Citations (Scopus)

Abstract

Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are frequently used for cantilever calibration, there is no consensus on the optimal calibration of soft and V-shaped cantilevers, especially those used in force spectroscopy. Therefore, in this study we aimed at establishing a commonly accepted approach to accurately calibrate compliant and V-shaped cantilevers. In a round robin experiment involving eight different laboratories we compared the thermal noise and the Sader method on ten commercial and custom-built AFMs. We found that spring constants of both rectangular and V-shaped cantilevers can accurately be determined with both methods, although the Sader method proved to be superior. Furthermore, we observed that simultaneous application of both methods on an AFM proved an accurate consistency check of the instrument and thus provides optimal and highly reproducible calibration. To illustrate the importance of optimal calibration, we show that for biological force spectroscopy studies, an erroneously calibrated cantilever can significantly affect the derived (bio)physical parameters. Taken together, our findings demonstrated that with the pre-established protocol described reliable spring constants can be obtained for different types of cantilevers.
Original languageEnglish
Pages (from-to)1659-1669
Number of pages11
JournalUltramicroscopy
Volume111
Issue number12
DOIs
Publication statusPublished - 2011

Keywords

  • Atomic force microscopy
  • Spring constant
  • Round robin experiment
  • Cantilever calibration

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