A microfluidic-based nanoscope

• Published in: Experiments in fluids 2002-11, Vol.33 (5), p.613-619
• Main Authors: STONE, S. W, MEINHART, C. D, WERELEY, S. T
• Format: Article
• Language: English
• Subjects: Applied fluid mechanics; Exact sciences and technology; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Scanning probe microscopes, components and techniques
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-001-0379-2

A novel technique for noninvasively measuring the shapes of walls with resolution approaching tens of nanometers is presented. The nanoscope measures local wall position by measuring the velocity of a fluid with micron-scale spatial resolution as it flows over a surface. The location of the wall is estimated by assuming the no-slip velocity condition at the wall and extrapolating the velocity profile to zero. Nanoscope measurements were obtained in a 30 x 300-micron channel. The wall shape of the glass microchannel was determined to be flat to within a root mean square uncertainty of 62 nm. Numerical simulations show that noise in the velocity measurements contributes significantly to uncertainty in wall position. The technique can be used to measure surfaces that are immersed in liquids and in geometries that do not provide exposed surfaces, where traditional nanoscope techniques such as scanning probe microscopes (SPM) are not applicable. (Author)