Adhesive Contact of Small-Volume Structure

Adhesive Contact of Small-Volume Structure Project Summary MEMS (microelectromechanical systems) and NEMS (nanoelectromechanical systems) have become exciting fields that explode onto the technological scene. The challenging issues in the development of MEMS and NEMS are the understanding of mechanical behavior on the micro scale and the incorporation of the understanding into the design of MEMS and NEMS devices to improve device's performance and reliability. Not much is known on the micromechanical behavior of small-volume structure, especially the microcontact behavior. It is therefore considered opportune to investigate the microcontact behavior of small-volume structure by using surface force techniques, such as nanoindentation as well as new devices, such as microwedge bending capable of directly testing small-volume structures. Intellectual merit: This research project integrates the characterization and modeling of smallvolume structure with the goals of addressing the effect of scaling-dependent mechanical properties on the contact behavior of small-volume structure and of improving the design methodology for the rapid introduction of advanced microfabrication technologies used in the MEMS and NEMS industries. The principal research objectives of the project are: 1) to develop a new microwedge test that probes the microcontact behavior of small-volume structure, 2) to determine the effect of the scale-dependence of mechanical properties on the adhesive contact, and 3) to establish a relation between the adhesion energy, pull-off force and contact deformation. To achieve the research objectives, nanoindentation and microwedge techniques will be used to characterize the adhesive contact of small-volume structure made of MEMS materials, such as polycrystalline silicon, silicon carbide and LlGA-nickel. Comprehensive characterization of the microstructure will be performed to establish the deterministic link between the microstructure and the micro contact deformation. Using the theory of surface elasticity and data from experiments and numerical simulation, a new relation between the surface stresses and the pulloff force as a function of mechanical properties and surface texture will be developed. This relation will help us search for contacts with a least possibility of adhesion in small-volume structure. A good understanding of the microcontact behavior of small-volume structure should result from this investigation. Broader impacts: It is envisioned that the research proposed here can lead to the optimization of design methodologies for the rapid introduction of advanced microfabrication technologies used in the MEMS and NEMS industries. It will extend our general understanding of the scalingdependent properties of small-volume structure as well as provide valuable engineering data for the design of MEMS and NEMS devices. Successful completion of the proposed research will produce a group of young engineers and scientists, who are experts in the characterization and modeling of small-volume structure. Moreover, the PI intends to use the research experience developed in this project as part of teaching materials in a new graduate and seniorundergraduate course, ME599/MSE599 "Nanoindentation and Surface Force Microscopy" to advance discovery and understanding while promoting teaching, training and learning.