Direct observation through membrane DOTM

A major advance vas made by Tony Fane and co-workers at the University of New South Wales when they developed a method to perform visual observation from the permeate side of the membrane. This technique, called direct observation through membrane (DOTM), was first described by Hodgson, PUlay and Fane [9] and then discussed more fully by Li et al. [10]. The key idea is to use a membrane which becomes transparent when wetted, and then observe partide deposition by placing a microscope on the permeate or back side of the membrane. Because of the relatively short focal length, compared to looking into the center of a membrane molecule from the side, high magnification may be used to observe individual particles as small as 1-10 pm in diameter. 

DOTM Direct observation through the membrane n Viscosity... 

A significant advance in optical characterization was made with the introduction of an approach now known as direct observation through the membrane (DOTM) [5, 6]. The microscope objective is positioned on the permeate side and focused through the permeate channel and the membrane onto the membrane surface on the feed side. Thus the membranes used must be transparent. Although this is a major limitation, significant findings have been made, as discussed elsewhere. 

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