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

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. 该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。Stambaugh与韩国首尔国立大学的Jhe Wonho博士和美国佛罗里达大学的Ho Bun Chan博士合作。液体在各种现象中发挥着重要作用。尤其是水，是生命的基础。然而，尽管如此，它的一些性质和液体的性质，一般来说，仍然没有得到很好的理解。当液体样品被限制在空间尺寸为纳米级的空间中时尤其如此。在这里，已经发现水表现出许多有趣和新颖的特征，包括冰相的表现，而不是通常在散装样品和固体状有序的展览。两个表面之间的薄纳米水层是每天摩擦的原因，也是摩擦学中许多现象的背后。纳米级水在生物过程中也起着至关重要的作用，如蛋白质折叠和酶激活。不幸的是，由于大量水的短程有序性和水分子的不断搅动，这些特征在大多数情况下很难研究。近年来，纳米技术的进步已经允许在越来越小的长度尺度上制造和探测系统。这些进展提供了在纳米尺度上研究液体样品的手段。首尔国立大学的Wonho Jhe教授最近的工作是使用原子力显微镜研究纳米级水柱在小空间中的形成。这些研究表明，纳米级的水样实际上具有弹性;这一特征被在散装水样中观察到的粘性所掩盖。 这项研究的重点是实验探测纳米级液体柱，特别是水的性质。这是通过结合两种实验技术来测量力梯度和纳米水柱施加的力来完成的。第一种技术涉及使用原子力显微镜测量通过小振幅调制方法操作的力梯度。第二种使用敏感的微机电（MEMS）力传感器来测量由柱施加的力。这两种技术的结合提供了一种新的方案，用于研究之间形成的原子力显微镜？的悬臂梁和MEMS力传感器。具体特征包括湿度对粘附力的影响、水的弹性和粘性以及毛细凝结的松弛和成核时间。 这些结果将有助于我们了解纳米水在生物过程中的作用，以及粘附力对扫描探针显微镜和MEMS性能的影响。

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.