STUDY OF SELF-ASSEMBLED MONOLAYERS OF N-ALKANETHIOL ON A SURFACE-PLASMON RESONANCE FIBER OPTIC SENSOR

Surface plasmon resonance (SPR) is a powerful technique for direct sen sitive (bio)chemical detection. This phenomenon can be used to measure the refractive index of either bulk chemical samples or chemically se nsing thin layers. In this work, a surface plasmon resonance fibre opt ic sensor has been developed. A 50 nm thick silver film is deposited b y thermal evaporation onto the silica core of the optical fibre. To pr otect silver from oxidation, the evaporated silver film was covered wi th self-assembled monolayers (SAMs) of long-chain alkanethiols (1-octa decanethiol), To characterize these SAMs, silver films evaporated onto macroscopic glass surface as test samples and several techniques such as contact-angle measurements (sessile drop method), X-ray photoelect ron spectroscopy, and atomic force microscopy were used. Such a modifi ed surface showed a high contact angle with water which remains stable after a one month stay in aqueous media. Similarly, a SPR fibre optic sensor showed no ageing problem, when kept in the same conditions.