TOWARD SOL-GEL-PROCESSED CHEMICAL SENSING PLATFORMS - EFFECTS OF DOPANT ADDITION TIME ON SENSOR PERFORMANCE

The development of new chemical and biochemical sensing schemes has be en a topic of growing interest. Simplicity of preparation and mild pro cessing conditions have made sol-gel-derived composites attractive for many chemical sensing schemes. A portion of our research centers on u sing sol-gel-processed materials for the development of selective sens ors. Over the years we have aimed to characterize the analytical perfo rmance of these types of sol-gel-based sensing platforms. In the cours e of this work we recently discovered that the time (prior to casting) when the sensing chemistry is actually doped into the sol-gel process ing solution plays a critical role in a given sensor's analytical perf ormance. In this paper we report on the effects of doping time on the behavior of a model organic dopant (pyrene) sequestered within sol-gel -derived microfiber tips and films. We use O-2 as the analyte and dete rmine the sensor sensitivity and temporal response as a function of do ping time. We also quantify the local dipolarity of the immediate envi ronment surrounding the average pyrene molecule as a function of dopin g time.