How to Measure Forces when the Atomic Force Microscope shows Non-Linear Compliance

TL;DR

This paper presents a spreadsheet-based algorithm for accurately measuring forces with an atomic force microscope, accounting for non-linear behaviors and artifacts to improve calibration and data analysis.

Contribution

It introduces a comprehensive data analysis method that considers non-linear cantilever behavior, tilt, friction, and artifacts, automating zero separation determination.

Findings

Accurate force measurement in silica-silica interactions

Automatic zero separation determination

Enhanced calibration of cantilever spring constant

Abstract

A spreadsheet algorithm is given for the atomic force microscope that accounts for non-linear behavior in the deflection of the cantilever and in the photo-diode response. In addition, the data analysis algorithm takes into account cantilever tilt, friction in contact, and base-line artifacts such as drift, virtual deflection, and non-zero force. These are important for accurate force measurement and also for calibration of the cantilever spring constant. The zero of separation is determined automatically, avoiding human intervention or bias. The method is illustrated by analyzing measured data for the silica-silica drainage force and slip length.