Calibrating conservative and dissipative response of electrically-driven quartz tuning forks

TL;DR

This paper introduces a high-precision calibration method for quartz tuning fork sensors that simultaneously measures conservative and dissipative forces, improving quantitative nanomechanical measurements in AFM.

Contribution

It presents a novel calibration technique that directly applies controlled forces to measure both force gradient and damping coefficient simultaneously.

Findings

Frequency shift depends on both conservative and dissipative forces.

Calibration method is effective and applicable to various sensors in NC-AFM.

The approach enhances quantitative force measurements in nanomechanics.

Abstract

Determining sensor parameters is a prerequisite for quantitative force measurement. Here we report a direct, high-precision calibration method for quartz tuning fork(TF) sensors that are popular in the feld of nanomechanical measurement. In the method, conservative and dissipative forces with controlled amplitudes are applied to one prong of TF directly to mimic the tip-sample interaction, and the responses of the sensor are measured at the same time to extract sensor parameters. The method, for the frst time, allows force gradient and damping coeffcient which correspond to the conservative and dissipative interactions to be measured simultaneously. The calibration result shows surprisingly that, unlike cantilevers, the frequency shift for TFs depends on both the conservative and dissipative forces, which may be ascribed to the complex dynamics. The effectiveness of the method is testifed by force spectrum measurement with a calibrated TF. The method is generic for all kinds of sensors used for non-contact atomic force microscopy(NC-AFM) and is an important improvement for quantitative nanomechanical measurement.