Preparation features of the end-faces of quartz optical fibers for bacteriorhodopsin films deposition

Abstract

In order to improve the performance of sensors based on bacteriorhodopsin with a sensitive element at the end-face of the quartz optical fiber, we have proposed and developed the technology of mechanical grinding and polishing of the end-faces of quartz optical fibers via adapting the existing methods and techniques for grinding and polishing of glass and glassy materials. After grinding the end-face of the quartz optical fiber was subjected to additional chemical treatment in a mixture of hydrogen peroxide and sulfuric acid in 30:70 (piranha) ratio.

The results of the grinding and polishing technique adaptation for the glass-like materials for the treatment of the end-faces of quartz optical fibers and the results of investigations of the polished end-faces of quartz optical fibers with the help of optical and atomic force microscopy and comparison of their characteristics with the raw fibers are presented. In addition, the results of investigations of film structures based on bacteriorhodopsin in gelatin and sol-gel matrices deposited on the end-faces of quartz optical fibers pretreated with the help of the proposed procedure are presented.

Microscopic studies of the surface of the end-faces of quartz optical fibers prepared with the help of the technology that we have worked out indicate that the surface roughness of the polished end-faces does not exceed 10 nm. Investigation of the characteristics of the obtained films showed that, at the end-faces of the quartz optical fiber, a homogeneous transparent film is formed, which has a good adhesion. Spectral studies of the obtained films showed the presence of a clear absorption band of bacteriorhodopsin at 570 nm, which indicates that it keeps its optical characteristics.