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 been a topic of growing interest. Simplicity of preparation and mild processing conditions have made sol-gel-derived composites attractive for many chemical sensing schemes. A portion of our research centers on using sol-gel-processed materials for the development of selective sensors. Over the years we have aimed to characterize the analytical performance of these types of sol-gel-based sensing platforms. In the course of this work we recently discovered that the time (prior to casting) when the sensing chemistry is actually doped into the sol-gel processing solution plays a critical role in a given sensor's analytical performance. 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 determine the sensor sensitivity and temporal response as a function of doping time. We also quantify the local dipolarity of the immediate environment surrounding the average pyrene molecule as a function of doping time.