Ultrathin film composite membranes approach

This approach is based on a concept borrowed from the membrane-based separations area - ultrathin film composite membranes. Ultrathin film composite membranes consist of an ultrathin (less than ca. 100 nm-thick) polymer dcin coated onto the surface of a microporous support membrane. These composite membranes have made a tremendous impact on the field of membrane-bas separations because they can offer high permeate flux without sacrificing chemical selectivity. These two qualities (high permeate flux and high chemical selectivity) are also required in polymeric barrier layers in chemical sensors. Therefore, the ultrathin film composite membrane concept ould be applicable to sensor design. In this paper we present proof of this concept by riiowing the response characteristics of a prototype glucose sensor based on an ultrathin frlm composite membrane. 

There are several potential routes to the preparation of composite reverse osmosis membranes, whereby the ultrathin semipermeable film is formed or deposited on the microporous sublayer.1 2 The film can be formed elsewhere, then laminated to the microporous support, as was done in the earliest work on this membrane approach. Or it can be formed in place by plasma polymerization techniques. Alternatively, membrane polymer solution or polymer-forming reactants can be applied in a dipcoating process, then dried or cured in place. The most attractive approach from a commercial standpoint, however, has been the formation of the semipermeable membrane layer in situ by a classic "non-stirred" interfacial reaction method. Several examples of membranes made by this last approach have reached commercial status. 

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