A fluorescence energy transfer sensor for metal ions

There is presently considerable interest world-wide in fabricating sensors based on miniaturized analytical techniques encapsulated in sensing elements with an inbuilt intelligence capable of distinguishing between different analytes. For example, the measurement of metal ion concentration in fluid media is a common requirement when monitoring many types of industrial processes and chemical reactions. In addition there is an increasing requirement for the remote determination of trace elements in water.We report a new type of remote optical sensor of metal ions in solution based on fluorescence lifetime quenching due to dipoledipole energy transfer across a polymer-water interface. Ion selectivity is provided by spectral overlap between the sensor fluorescence and metal ion absorption. The sensor is demonstrated in the detection of cobalt ions in water at levels down to 17 fig