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Accurate Noncontact Calibration of Colloidal Probe Sensitivities in Atomic Force Microscopy



Koo-Hyun Chung, Gordon A. Shaw, Jon R. Pratt


The absolute force sensitivities of colloidal probes comprised of atomic force microscope, or AFM, cantilevers with microspheres attached to their distal ends are measured. The force sensitivities are calibrated through reference to accurate electrostatic forces, the realizations of which are described in detail. Furthermore, the absolute accuracy of a common AFM force calibration scheme, known as the thermal noise method, is evaluated. It is demonstrated that the thermal noise method can be applied with great success to colloidal probe calibration in air and in liquid to yield force measurements with relative standard uncertainties below 5%. Techniques to combine the electrostatics-based determination of the AFM force sensitivity with measurements of the colloidal probe s thermal noise spectrum to compute noncontact estimates of the displacement sensitivity and spring constant are also developed.
Review of Scientific Instruments


Atomic Force Microscope, Colloidal Probe, Electrostatic Force, Noncontact Calibration


Chung, K. , Shaw, G. and Pratt, J. (2009), Accurate Noncontact Calibration of Colloidal Probe Sensitivities in Atomic Force Microscopy, Review of Scientific Instruments, [online], (Accessed April 18, 2024)
Created June 15, 2009, Updated February 19, 2017