Calibration of the oscillation amplitude of electrically excited scanning probe microscopy sensors

TL;DR

This paper introduces a new calibration method for electrically driven AFM sensors that measures electrical energy input to determine oscillation amplitude, improving quantitative surface analysis.

Contribution

A novel calibration technique based on electrical energy input is proposed, applicable to various piezoelectric resonators, enhancing measurement accuracy in AFM.

Findings

Calibration factor agrees with thermal noise spectrum method

Applicable to quartz tuning forks and qPlus configurations

Improves quantitative surface property measurements

Abstract

Atomic force microscopy (AFM) is an analytical surface characterization tool which can reveal a sample's topography with high spatial resolution while simultaneously probing tip-sample interactions. Local measurement of chemical properties with high-resolution has gained much popularity in recent years with advances in dynamic AFM methodologies. A calibration factor is required to convert the electrical readout to a mechanical oscillation amplitude in order to extract quantitative information about the surface. We propose a new calibration technique for the oscillation amplitude of electrically driven probes, which is based on measuring the electrical energy input to maintain the oscillation amplitude constant. We demonstrate the application of the new technique with quartz tuning fork including the qPlus configuration, while the same principle can be applied to other piezoelectric resonators such as length extension resonators, or piezoelectric cantilevers. The calibration factor obtained by this technique is found to be in agreement with using thermal noise spectrum method for capsulated, decapsulated tuning forks and tuning forks in the qPlus configuration.