Simultaneous sensing of the chemical and physical environment with smart nanocomposites prepared from hybrid colloids

Sensing environmental parameters such as temperature, volatile organic molecules, relative humidity, ionic strength or pH can be achieved in many different ways with devices exploiting the sensing capability of materials resulting from their solid state properties (e.g. of semiconductors, fluorescent probes, etc.) or from wet chemistry. However, there is a growing demand for cheap, miniaturized, adaptable sensors, in particular for packaging, garment and biomedical applications. Selectivity and multifunctionality are additional issues that cannot generally be met by the current state-of-the art sensors, unless using relatively sophisticated techniques or equipment. In particular, sensing pH with solid state devices is a sought after alternative to conventional pH sensing by membrane electrodes requiring calibration and relatively large volumes of solution to be analysed. An attractive option with a broad range of potential applications involves using a resistive device in which the pH sensing mechanism relies on the modification of the dielectric properties of the coating of an electrode, allowing fast pH measurements even from microliter-sized samples. As a general strategy for the fabrication of single-use, disposable sensing devices, possibly capable of simultaneous sensing of multiple environmental physical and chemical parameters we are investigating a sensor architecture based on a resistive electrode coated with a smart polymer nanocomposite as the sensing material.