Development of submicron chemical fiber optic sensors

Optical fiber sensors have several advantages over electrical-based sensors in many applications in chemistry and biology, but not with respect to minaturization and response time. Here the authors describe a near-field optical technique that enables the development of submicron-sized optical fiber sensors. The technology is based on nanofabricated optical fiber tips and near-field photoinitiated polymerization. Multimode or single-mode optical fibers are drawn into submicron optical fiber tips and then coated with aluminum to form submicron optical fiber light sources. Submicron pH sensors, as an example for small sensors, have been prepared by incorporating fluoresceinamine into an acrylamide-methylenebis(acrylamide) copolymer that is attached covalently to a silanized fiber tip surface by photoinitiated polymerization. The sensors have demonstrated their spatial resolving abilities in measuring the pH of buffer solutions inside micron-size holes in a polycarbonate membrane. These submicron pH sensors have millisecond response times due to their extremely small sizes. 20 refs., 6 figs.