International Research Fellowship Program: Investigation of Nanoscale Water Columns using a MEMS Force Sensor

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0853104StambaughThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Corey A. Stambaugh to work with Dr. Jhe Wonho at Seoul National University in Korea and with Dr. Ho Bun Chan at the University of Florida in the US.Liquids play an important role in a variety of phenomena. Water, in particular, is fundamental to life. Yet despite this, several of its properties and those of liquids, in general, are still not well understood. This is especially true when the liquid samples are confined to spaces whose spatial dimensions are on the nanoscale. Here, water has been found to exhibit many interesting and novel features including the manifestation of ice phases, not typically seen in bulk samples and exhibition of solid-like orderedness. Thin nanometer layers of water between two surfaces are responsible for every day experiences with friction and are behind many of the phenomena seen in tribology. Nanoscale water also plays an essential role in biological processes such as protein folding and enzyme activation. Unfortunately, due to the short-range order of bulk water and constant agitation of water molecules, these features prove difficult to investigate under most circumstances. In recent years, advances in nanotechnology have allowed for the fabrication and probing of systems on increasingly smaller length scales. Such advances have provided the means to study liquid samples on the nanoscale. Recent work by Prof. Wonho Jhe at Seoul National University examined the formation of nanoscale water columns in small spaces using an atomic force microscope. These studies have shown that nanoscale water samples actually possess elastic properties; a feature obscured by the viscous properties observed in bulk water samples. This research focuses on experimentally probing the properties of nanoscale liquid columns, specifically water. This is done by combining two experimental techniques to measure both the force gradient and the force exerted by the nanoscale water columns. The first technique involves measuring the force gradient operated via the small amplitude-modulated method using an atomic force microscope. The second uses a sensitive microelectromechanical (MEMS) force sensor to measure the forces exerted by the columns. The combination of the two techniques provides a novel scheme for studying several features of the nanoscale water columns that are formed between the atomic force microscope?s cantilever and the MEMS force sensor. The specific features include the impact of humidity on the adhesive force, the elasticity and viscosity of water, and the relaxation and nucleation time of capillary condensation. These results will contribute to our understanding of the role nanoscale water can play in biological processes and of the effect the adhesive force has on the performance of scanning probe microscopy and MEMS.