| The purpose of this research is to demonstrate potential applications of sol-gel derived fluorescence sensors for calcium. Recently, there has been interest in the development of sol-gel sensors. The sol-gel technique is a convenient way to synthesize a host matrix for a variety of sensor chemistries. Sol-gels are silica based ceramic materials which are very effective as host matrices. Sol-gels can be used to effectively immobilize heat-sensitive compounds including biochemical compounds, active proteins and organic molecules. The basis of the sol-gel process is hydrolysis of alkoxide precursors by acid catalysis followed by polycondensation of the hydroxylated units to construct a silica gel. The advantages of a sol-gel sensor platform include optical transparency, structural stability, and ease of processing.;A novel approach using both fiber optic and thin film formats with sol-gel matrices to develop sensors has been attempted in this research. Over the past few years, the uses of optical fibers in spectroscopy have increased rapidly. The optical fiber is often a convenient vehicle to perform optical measurements outside the laboratory environment. Generally, they are inexpensive, flexible, easy to assemble, small and light weight. Films and coatings represent the earliest commercial application of sol-gel technology. Compared with a monolith sensor, sol-gel derived thin film sensors have a shorter diffusion path length for the analyte. Thus, the response times can be decreased and the sensor performance can also be improved. Dip coating is most effective because a homogeneous coating can be deposited onto substrates of large dimensions and complex geometries. This thesis focuses on the method of sol-gel derived thin films by dip coating. In the process of dip-coating, the substrate is immersed into the sol-gel solution and then withdrawn at a constant rate. The properties of both fiber optic and thin film sensors are illustrated using reproducibility, reversibility and responsivity data. |
