A Sensor for Measuring Gel Phase-Transition Temperature, with Potential as a Metal Ion Detector

This paper describes a sensor employing a gel formed from an interpenetrating polymer network of poly(vinyl alcohol) and a copolymer of N-isopropylacrylamide and acrylic acid. This gel exhibits a continuous volume-phase transition that is strongly dependent on the presence of polyvalent metal ions in the gel solvent. A sensor apparatus has been constructed that estimates, in real time, the transition temperature of a gel. When this sensor is loaded with a gel sensitive to metal ions, it could be used to detect the presence and identity of metal ions in a solution.