POTENTIOMETRIC PH SENSORS BASED ON URETHANE-ACRYLATE PHOTOCURABLE POLYMER MEMBRANES

A pH sensitive membrane based on a photocurable urethane-acrylate poly mer with dioctylsebacate as plasticiser and tetradodecylamine as ionop hore is described. This kind of polymer has been chosen as the membran e matrix because it is prepared and deposited more easily than PVC mem branes. The deposition procedure, compatible with IC technology, permi ts the production of 100 mu m thick membranes after few s of UV light exposure. The composition of the membrane (monomer, cross-linker, sens itive ion-pair and plasticiser) has been studied to achieve good mecha nical properties and optimal sensor response. This pH membrane has bee n 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 f or sensor construction and its promising future application to urea de termination by deposition of an enzymatic membrane based on the same p olymer on the pH membrane developed. (C) 1998 Elsevier Science S.A. Al l rights reserved.