Potentiometric pH sensors based on urethane-acrylate photocurable polymer membranes

A pH sensitive membrane based on a photocurable urethane-acrylate polymer with dioctylsebacate as plasticiser and tetradodecylamine as ionophore is described. This kind of polymer has been chosen as the membrane matrix because it is prepared and deposited more easily than PVC membranes. The deposition procedure, compatible with IC technology, permits the production of 100 mu m thick membranes after few s of UV light exposure. The composition of the membrane (monomer, cross-linker, sensitive ion-pair and plasticiser) has been studied to achieve good mechanical properties and optimal sensor response. This pH membrane has been tested using a potentiometric transducer based on an all-solid-state design. A sensitivity of 55 mV pH(-1) and a linear range from pH 2 to 10 was obtained with this sensor. The long-term stability was up to 9 months, which is comparable with PVC membranes. The results obtained with this polymer demonstrate the feasibility of using this material for sensor construction and its promising future application to urea determination by deposition of an enzymatic membrane based on the same polymer on the pH membrane developed. (C) 1998 Elsevier Science S.A. All rights reserved.