The goal of this collaborative research is to identify and model key interfacial systems in which reproducible stick-slip and steady-sliding behaviors occur in micromachined structures. A central issue is the relationship between the structure of organic monolayer coatings applied to the interfaces, and the resulting kinetic phase diagrams. This study will create a scientific toolset to enable investigations of stick-slip and steady-sliding behavior. The friction test system consists of a long-travel high-force linear actuator pulling a calibrated spring and a friction block to which a controllable normal force is applied. The test apparatus will be imaged by a high-speed video camera.
Friction-based micromachined linear actuators have broad potential applications of significant technological importance including nanometer-scale positioning of optical components, data storage, microvalve flow control and microrobotics. This actuator technology holds the potential to revolutionize fiber communications, lab-on-a-chip diagnostics and microassembly techniques. The performance and reliability of these actuators depends strongly on control of the contacting interface and understanding of its behavior under various loading and environmental conditions. The proposal?s educational component includes the development of complimentary Senior/Graduate elective courses at Carnegie Mellon and Auburn Universities, entitled "Experimental Micro- and Nanomechanics" and "Thin Film Deposition and Characterization Methods." A summer exchange program will ensure that students learn experimental techniques taught at each university. Outreach will be accomplished by interacting with high-school journalism classes which will develop videos stimulating interest in engineering.
This collaborative research project between Auburn University and Carnegie Mellon University was undertaken to better understand and enable the prediction of friction properties of micromachined surfaces. The platform used to study microscale friction are micromechanical devices which have tailored surface properties. The test devices were investigated using a variety of methods to measure their friction properties at a variety of loads, and sliding rates. Data collected from these devices along with knowledge about their fundamental surface properties has been used to understand and quantify microscale friction for microdevices. Auburn University's contribution to this collaborative effort was to apply surface treatments to micromachine devices and characterize the fundamental properties of those surface treatments. Surface treatments such as the application of self-assembled monolayers were applied and characterized with contact angle analysis, ellipsometry, atomic force microscopy and in some instances FTIR spectroscopy. Additionally, some basic testing of devices was performed at Auburn University, to ensure that devices sent to Carnegie Mellon were functional. In short, Auburn University carried out test sample preparation for researchers at Carnegie Mellon to test. Since many of the major results of this project have to do with relationships of measured test data to frictional performance, the overall outcomes are still pending completion of testing and analysis at Carnegie Mellon. To date, one journal article has been published and another is in preparation. Numerous presentations at technical conferences have been given. The efforts of Carnegie Mellon for this project are still ongoing, and additional results are forthcoming.
