Calibration of effective spring constants of colloidal probes using reference cantilever method

• We propose a method of directly calibrating the effective spring constant of a colloidal probe’s cantilever by the reference cantilever method.
• The effective spring constants of the colloidal probes by the proposed method were compared to those obtained by the FEA.
• The importance of the colloidal probe’s spring constant in mechanical tests was investigated by investigating force distance curves and nanoscale wear test results.
• The von Mises stress distributions for contact between the spherical particle and the sample surface were obtained.

The precise measurement of the effective spring constant of a colloidal probe's cantilever is very important for the accurate application of a desired contact load to a sample surface since the contact load is determined by multiplying the effective spring constant of the cantilever and its deflection. This paper presents a method of directly measuring the effective spring constant of a colloidal probe by the reference cantilever method. The distinctive feature of the reference cantilever method in this study is that the reference cantilever has a tip. The tip determines the location of the loading point on the reference cantilever and enables detecting the loading point on the colloidal probe's cantilever by monitoring the change in a force distance curve depending on the contact point between a spherical particle and the tip. The effective spring constants of the colloidal probes measured by the proposed method are compared to those determined by finite element analysis (FEA). The importance of calibrating the effective spring constant of the colloidal probe in applied forces and mechanical tests is investigated by comparing force distance curves and nanometer-scale wear test results obtained at two different spring constant settings.

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