2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Quick “easy?!” determination of the diameter of nanocapillaries

A. Lutfurakhmanov, R. Sailer, S.Z. Janjua, I. Akhatov and D.L. Schulz
North Dakota State University, US

nanocapillary, flow, diameter

Precise measurements of the inner diameter (ID) of nanocapillaries are of interest to many areas of study due to the high sensitivity of gas and liquid flows with respect to the radius of the capillary. Applications ranging from biological transport to electronics manufacture require knowledge of fluid transport properties through passages with nanoscale dimensions. In the microscale, volume flow and fluid velocity are quadratic and squared functions of the capillary radius, respectively. While these relationships hold for most fluids in the nanoscale, the dependence on the ID is extreme with small variations in diameter leading to significant variations in flow properties. The current approach for measuring nanocapillary ID (i.e., FESEM) is time consuming and typically requires a conductive coating. We have developed a simple, nondestructive test to accurately determine the diameter of nanocapillaries based on bubble point. The apparatus consists of a high pressure gas source connected to a nanopipette where the tip is located under the surface of a liquid. Bubble rate is determined as a function of pressure using an optical microscope. The Laplace relationship between surface tension induced pressure and capillary radius and our mathematical models that describe fluid flow through nanocapillaries will be discussed.

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Nanotech 2007 Conference Program Abstract


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