Hydroxyethyl) methacrylate gels are transparent, chemically and thermally stable with increased resistance to dehydration. PolyHEMA coated sensors exhibited well developed peaks, of pH dependent position, although increase in capacitance was also notable(Figure ). No deterioration of the signal was observed, during repeated measurements in buffer solutions. Prolonged incubation in cell culture medium resulted in complete loss of the signal, and no peaks could be observed after two week long incubation.