Interfacial force microscope

Joyce, S.A., Houston, J.E. and Michalske, T.A., Differentiation of topographical and chemical structures using an interfacial force microscope. Appl. Phys. Lett., 60(10), 1175-1177 (1992). 

During this past decade, SPM has been widely used as a technique for determining nanometer-scale mechanical properties. However, only a few applications of this method have so far been reported for studying tribofilms. Norton and coworkers investigated the use of an interfacial force microscope (IFM) for examining the difference in modulus and shear strength among various ZDDP tribofilms based on... 

Bunker, B.C. et al. (2003) Direct observation of photo switching in tethered spiropyrans using the interfacial force microscope. Narw Lett., 3, 1723-1727... 

Carpick R W, Agrait N, Ogletree D F and Salmeron M 1996 Measurement of interfacial shear (friction) with an ultrahigh vacuum atomic force microscope J. Vac. Sc/. Technol. B 14 1289... 

Complementary to the SFA experiments, SFM techniques enabled direct, non-destructive and non-contact measurement of forces which can be as small as 1 pN. Compared to other probes such as optical tweezers, surface force balance and osmotic stress [378-380], the scanning force microscope has an advantage due to its ability in local force measurements on heterogeneous and rough surfaces with excellent spatial resolution [381]. Thus, a force-distance dependence measured from a small surface area provides a microscopic basis for understanding the macroscopic interfacial properties. Furthermore, lateral mapping... 

This is the most dramatic development because surface features from interatomic spacing to fractions of a millimeter can be studied with the same instrument. The various systems that have been analyzed by both STM and AFM are many and varied (Table 15.1). Additionally, surface force microscopes (SFM) allow the possibility of measurement of interfacial forces (at nanometer distances). 

Summary. Scanned probe methods for imaging electrochemical deposition on surfaces are now well established. For such methods the smface structure at the atomic scale can be measured so that surface strains may be inferred. Here we demonstrate how extremely sensitive and fast stress sensors can be constructed from atomic force microscope (AFM) cantilevers for studies of interfacial processes such as adsorption and reconstruction. The surface stress sensor has submonolayer sensitivity for use in electrochemistry, whereby simultaneous cyclic voltammograms and stress changes can be recorded. This is demonstrated with measurements of the electrocapillary curve of gold, and stress changes associated with the underpotential deposition of silver on gold (111). 

The atomic force microscope (AFM) is a promising device for the investigation of materials surface properties at the nanoscale. Precise analysis of adhesive and mechanical properties, and particularly of model polymer surfaces, can be achieved with a nanometer probe. This study distinguishes the different contributions (chemical and mechanical) included in an AFM force-distance curve in order to estabhsh relationships between interfacial tip-polymer interactions and the surface viscoelastic properties of the polymer. 

In the previous section, it was noted that the microscopic displacement efficiency is largely a function of interfacial forces acting between the oil, rock, and displacing fluid. If the interfacial tension between the trapped oil and the displacing fluid could be lowered to 10 to 10 dyn/cm, the oil droplets could be deformed and could squeeze through the pore constrictions. A miscible process is one in which the interfacial tension is zero that is, the displacing fluid and the residual oil mix to form one phase. If the interfacial tension is zero, then the capillary number Nyc becomes infinite and the microscopic displacement efficiency is maximized. 

An understanding of multiphase microflows is critical for the development and application of microstructured chemical systems in the chemical industry. As one of the most important meso-scientific issues, interfacial science could be a bridge connecting microscopic molecular components and macroscopic fluid behaviors in these systems. Working together with viscous and inertial forces, the interfacial force also dominates complicated multiphase flow patterns and well-controlled droplets and bubbles. In this review, the generation mechanisms of different flow patterns and the break-up rules for droplets and bubbles in microchannels are introduced first. The effects of the adjustable fluid/solid interfaces, or so-called wetting properties, of microchannels on multiphase flow patterns, as well as microchannel surface modification methods, are then discussed. The dynamic fluid/fluid interfaces in multiphase microflows with variable... 

X. M. Xiong, S. 0. Guo, Z. L. Xu, P. Sheng, and P. Tong, Deveiopment of an atomic-force-microscope-based hanging-fiber rheometer for interfacial microrheology, Phys. Rev. E, 80, 061604 (2009]. 

The interaction between drops has been studied experimentally with different techniques [731]. The most important technique for studying interfacial forces across thin films is the thin film balance [699,732]. In fact, a whole class of thin film balances have been developed. They are described in detail in Sections 7.4 and 7.6. In another technique, two drops at the end of two capillaries are moved toward each other [733] or one drop is moved toward a planar interface [734]. The process is observed by optical microscopy. Direct force measurements have become possible with the atomic force microscope by attaching tiny oil drops to AFM cantilevers [270, 696]. Recently, such drops have also been produced in microfluidic channels [735]. 

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