Tribologically-Enhanced Encapsulated Microball Bearings for Reduced Friction and Wear in High-Performance Rotary Microactuators and PowerMEMS Devices

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Tribologically-Enhanced Encapsulated Microball Bearings for Reduced Friction and Wear in High-Performance Rotary Microactuators and PowerMEMS DevicesProposal Number: 0901411University of Maryland College ParkPI: Reza Ghodssi, Co-PI: Matthew McCarthyAbstractSummaryThe objective of this work is to develop high-performance rotary ball bearings for Microelectromechanical Systems (MEMS) using tribologically-enhanced thin-film coatings. Particular emphasis will be on the design, fabrication, and experimental characterization of UltraNanoCrystalline Diamond (UNCD), Silicon Carbide (SiC), Titanium Nitride (TiN), and Boron Nitride (BN) films as hard-coatings to reduce friction and wear in microscale rolling contacts. The results of this will be implemented in a low-friction, low-wear, and long-lifecycle microball bearing for rotary microactuators and PowerMEMS devices. These support mechanisms will be capable of continuous operation for speeds in excess of 100,000rpm and provide the stability and reliability necessary for the realization of high-speed micro-turbogenerators as well as accurate rotary positioning systems for directional sensors.Intellectual Merits The work proposed here constitutes fundamental research into the science and engineering of microfabricated ball bearing support mechanism including the effects of hard coatings to reduce friction and wear. It will specifically lead to reliable support mechanisms for use within various rotary MEMS devices. The design and engineering of MEMS-fabricated ball bearings using hard-coatings will allow the realization of these technologies for high-performance applications. The in-situ experimental investigation proposed here will comprehensively address the effects of materials, loading, and operation on microfabricated rotary bearings. This will be achieved through (1) bearing design and fabrication using thin-film coatings, (2) in-situ experimental characterization using integrated microturbine actuation, and (3) implementation of optimized bearings in microfabricated rotary actuators and PowerMEMS devices.Broader Impacts Research This technology will yield a low-friction/wear microball support mechanism necessary for the realization of several high-performance rotary micromachines. Ongoing research is being conducted on the development of compact micro-turbogenerators for small-scale cost-effective power generation and rotary actuator platforms for directional sensor systems. The reliable demonstration of such devices over long life-cycles would have a substantial impact on distributed autonomous systems such as micro-air-vehicles, portable power systems, and sensor networks.EducationThis research will complement the university?s well-established research and education programs in materials science and MEMS. The interdisciplinary scope of the proposed research covers three major areas: Materials, Electrical, and Mechanical Engineering. The project offers an excellent opportunity to engage senior undergraduate and graduate students in masters and doctoral-level research on materials engineering and its broader impact on the MEMS field. The PI has developed a two-semester multidisciplinary graduate-level course with an active laboratory component (Design, Fabrication, and Testing of MEMS and Microsystems). The proposed research will strengthen ongoing work developing ball-bearing supported micromachines in the PI?s group, the MEMS Sensors and Actuators Laboratory (MSAL), as well as the Maryland Nanocenter. The PI supervises a number of undergraduate and graduate students, the majority of whom are US citizens. The co-PI is a former NSF GK-12 Teaching Fellow, and currently a postdoctoral researcher. These activities will directly impact the nature of the interdisciplinary research curriculum, recruitment of outstanding students, and dissemination of knowledge through conferences and refereed journal publication