Novel Approach to Nanoindentation Using a Multiprobe System

Authors Eyup Cinar and Ferat Sahin  describe a unique approach to nanoindentation that utilizes a MultiView 4000 multiprobe setup with tuning fork technology to conduct AFM-based nanoindentation with power advantages for measurements on soft and compliant materials.  Their method relies on tuning fork actuation and a frequency-based feedback (instead of the classical amplitude based feedback), which enables a very precise measurement of tip-sample interactions that avoids instabilities such as adhesion ringing and jump to contact that plague conventional measurements.

In this novel and exciting method, a dual-probe setup (schematic shown below followed by actual setup) is implemented where one probe is a diamond-tipped indentation probe while the second AFM probe measures the displacement of the indentation probe.  The tuning fork actuation controls the motion of the diamond-tip probe, thereby bring unprecedented stability to this measurement.

The authors demonstrate initial results showing proof-of-concept of this approach to nanoindentation with indents on a silicon sample where the stage positions of the 2 probes is successfully monitored and force vs. displacement curves are collected as shown below.  They further simulate their results with finite element analysis that shows good agreement from the simulated level of force and experimentally obtained force for a given penetration depth.  These preliminary results demonstrate the exciting potential of this approach to nanoindentation, and further experiments are already underway to try this method on a variety of samples.  

Published:  IEEE Nano, Sahin and Cinar 2014

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