Optical sensors and biosensors based on sol–gel films

The sol–gel technology is being increasingly used for the development of optical sensors and biosensors, due to its simplicity and versatility. By this process, porous thin films incorporating different chemical and biochemical sensing agents are easily obtained at room temperature, allowing final structures with mechanical and thermal stability as well as good optical characteristics. In this article, an overview of the state-of-the-art of sol–gel thin films-based optical sensors is presented. Applications reviewed include sensors for determination of pH, gases, ionic species and solvents, as well as biosensors.