Friction is a common phenomenon, frequently experienced in daily life. The detrimental effects of friction are easy to point out: the squeaky door caused by unnecessary rubbing of the metal hinge parts, the heavy clothes dresser that is difficult to move across the floor, tire tread and brake pad wear caused by friction during abrupt car braking. Despite numerous negative examples of friction, there are also many devices and tasks dependent on friction. Maintaining traction on an icy sidewalk, warming one’s hands by rubbing them together, and playing a violin are just a few examples of the positive effects of friction.
Tribology is the study of friction, wear, and lubrication, and like many other scientific fields, historical tribology has grown out of the complex relationship between scientific curiosity and technological need. Mediating friction for technological improvement motivates better scientific understanding, which in turn brings about novel applications that make use of the newly-discovered fundamental concepts.
The goal of my research is to seek out a better understanding of the fundamental mechanisms of friction. I use the atomic force microscope (AFM) to determine nanoscale constitutive laws for friction and wear.
In this research, we work to uncover a more fundamental understanding of friction using the Atomic Force Microscope (AFM).
The AFM tip, typically with a 10-100 nm radius of curvature, is attached to a compliant cantilever spring. This tip is brought into contact with nominally flat surface. At low applied loads, the tip can form a nanometer-scale single contact point with the sample surfaces, thus providing, in principle, a well-defined interface. The cantilever’s deflections are recorded using, most commonly, a reflected optical beam. The normal and lateral forces can be measured with sub-nanoNewton precision, provided that appropriate calibration methods are used. The tip is rastered over the surface with sub-Ångstrom displacement precision in x, y, and z using piezoelectric scanning tubes.
A brand new state-of-the-art AFM was installed in the fall of 2007 in the Flater Nanotribology research lab. This system is designed and manufactured by Veeco Instruments in Santa Barbara, CA. This AFM is a MultiModeV NanoscopeV AFM.
Performing contact resonance methodology using an FPGA-based multifrequency lock-in amplifier
Undergraduate researchers: Lucas Ruge-Jones (2018-), Keegan Danielson (2017-), Megan Petzold (2017)
Developing methodology to quantify wear using only an AFM
Undergraduate researchers: Jared Barnes (2017-2018), Jesse Hitz Graff (2014-2016), Jayse Weaver (2015-2016)
To be published in Review of Scientific Instruments in Nov 2018.
Microscale investigation of bare and coated aluminum oxide surfaces
Undergraduate researchers: Jesse Hitz Graff (2014-2016), Steve Sorenson (2013-2015), Erik Linn-Molin (2012-2013), Luwa Matthews (2010-2012), Sarice Barkley (2010)
AFM tip deconvolution methods: "Pursuing improved atomic force microscope tip shape quantification methods at Luther College"
Undergraduate researchers: George Zacharakis-Jutz (2010-2011), Braulio Dumba (2008-2010), Isaac White (2007-2009)
This work is published in Ultramicroscopy:
E.E.Flater, G.E.Zacharakis-Jutz*, B.G.Dumba*, I.A.White*, C.A.Clifford, "Toward Easy and Reliable AFM Tip Shape Determination using Blind Tip Reconstruction", Ultramicroscopy 146 (2014) p.130-143.
If you are interested is using our MATLAB-based blind tip reconstruction algorithms, they are available for free at nanoHUB.org.