Surface modification, optical fibers

Lin, C. H., Lee, G. B., Fu, L. M., and Chen, S. H. (2004). Integrated optical-fiber capillary electrophoresis microchips with novel spin-on-glass surface modification. Biosens. Bioelectron. 20, 83—90. 

Surface modification of optical fiber can be categorized into two groups (i) physical adsorption (non-covalent bonding), and (ii) covalent bonding. 

In addition to electrochemical polymerization, reactive monomers can be polymerized onto surfaces by using radio frequency (rf) plasma polymerization [194-197]. In this technique an electric discharge through the vapor forms a reactive plasma that chemically modifies the surface. Examples of applications of rf plasma-polymerized surfaces include the formation of (C2F4) films on fiber optic sensors for detection of volatile organics [198] and the formation of alkylamine surfaces on glass fibers by plasma treatment for subsequent chemical modification [199]. 

Ordered particle packings are also being used in other sensor type applications. Asher et al. ° described a system, where colloidal arrays of polymer particles were embedded in a gel-matrix. Changes in the environment of the particles caused the structures to shrink or expand, which could then be measured through the changes in the optical properties, as exemplified in Fig. 4. The same general idea can be applied to silica particles. This way, very specific sensors could be created when combined with appropriate surface modifications of the silica particles. The latter could be attached to the end of optical fibers or produced as a multisensor array on a chip. 

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