Imaging Membranes Using Atomic Force Microscopy

Takeyasu, K., Omote, H., Nettikadan, S., Tokumasu, R, Iwamoto-Kihara, A., and Futai, M. 1996. Molecular imaging of Escherichia coli FOFl-ATPase in reconstituted membranes using atomic force microscopy, FEBS Lett 392,110-113. 

Ito, Y., Park, Y.S. and Imanishi, Y. 1997b. Imaging of pH-sensitive polymer brush on a porous membrane using atomic force microscopy in aqueous solution. MacromoL o Commm. 18 221-224. 

Image analysis has been used to characterize the pore structure of synthetic membrane materials. The Celgard films have also been characterized by scanning tunneling microscopy, atomic force microscopy, and field emission scanning electron microscopy. The pore size of the Celgard membranes can also be calculated from eq 5, once the MacMullin number and gurley values are known. 

The atomic force microscopy technique is now widely used for the study of membrane surfaces. It has become an important tool of imaging the surface of materials to atomic-level resolution, and this technique does not need any special sample preparation, which is essential for SEM and TEM. AEM can show three-dimensional images of the surfaces. Paredes et al. has written an excellent review on the application of AEM for the characterization of microporous and mesoporous materials [16]. 

An atomic force microscope uses the deflection produced in a fine tip by interactions with atoms in the surface of a membrane to reconstruct the surface structure of that membrane. A piezoelectric drive moves the sample surface under the tip. The motions of the tip are converted into a three-dimensional image of the surface. Atomic force microscopy requires no surface preparation so that the membrane can be observed in its normal environment. 

Figure 5.46. Atomic force microscopy image (left) of a modified NF-270 membrane (size of image is ca. 1 X 1 pxa) and TEM cross sectional image (right) of the same membrane. (From Freger et al. [212], (2002) Elsevier used with permission.)...

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