On the importance of precise calibration techniques for an atomic force microscope

Proper calibration of any instrument is vital to an investigator's ability to compare laboratory experiments, as well as to draw quantitative relations between experimental results and the real world. For the atomic force microscope, knowledge of quantities such as the probe spring constant, the piezoactuator voltage/height response, and the probe radius of curvature is necessary when transforming raw data into height, separation and force. These parameters are also prerequisites when applying mathematical models to the collected data. In this communication, we adapt existing techniques of quantifying these parameters to our equipment and show differences between the adjusted parameters and those provided by the manufacturer. The total statistical uncertainty attributable to these parameters was calculated as > 1500% using the manufacturers' values. After adjustment, this contribution drops to approximately 20%. The combined effect of quantifying these parameters, which had previously not been explored in concert, demonstrates the necessity of properly understanding one's equipment in order to generate reproducible and credible experimental results.