Ion-selective sensors incorporating strongly adhesive polymeric membranes

Chemical-selective membranes having matrices of polyvinyl chloride (PVC)/(hydroxylated PVC), polyurethane/(hydroxylated PVC), and moisture-curable silicone rubber are compared to conventional PVC membranes in terms of adhesion to silicon nitride. A well-controlled peel test, developed for this evaluation, yields repeatable, quantitative results for both wet and dry membranes. Polyurethane and silicon membranes have much better adhesion to the sensor surface than do PVC or hydroxylated PVC. The hydroxylated PVC- and polyurethane-based membranes have electrochemical performance equivalent to that of PVC membranes in terms of slope, detection limit, and selectivity. Though the electrochemical properties of the silicone-matrix membrane are degraded somewhat by its high resistance, it has extremely good adhesion.<>