High Speed Friction Microscopy and Nanoscale Friction Coefficient Mapping

TL;DR

This paper introduces a high-speed AFM-based technique for mapping nanoscale friction coefficients across heterogeneous surfaces at velocities up to 2 cm/sec, enabling rapid and accurate tribological analysis relevant to micro- and nano-devices.

Contribution

A novel high-speed friction coefficient mapping method using AFM that significantly accelerates nanoscale tribology measurements at realistic device velocities.

Findings

Friction maps can be generated at 2 mm/sec, matching traditional methods.

Friction properties of mica measured from 200 μm/sec to 2 cm/sec.

Technique applicable to heterogeneous surfaces and relevant for MEMS and biological devices.

Abstract

As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for Friction Coefficient Mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm/s for microfabricated SiO2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ~1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 {\mu}m/sec up to 2 cm/sec. While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems.