Screen-printable sol-gel ceramic carbon composite pH sensor with a receptor zeolite

A screen-printable method is proposed to prepare a ceramic carbon composite sensor for pH determination. The pH-sensing membrane of the sensor is prepared by sol-gel, graphite powder and zeolite, in which zeolite is used as a receptor of proton. The fabrication of this ceramic carbon sensor includes three steps: preparing electrode slides, making a pH-sensing composite ink and screen-printing the ink on electrode slides. Optimum conditions for the ceramic carbon composite film are established, and characters of the pH electrode (stability, reproducibility, lifetime and conductivity) are examined comparing with glass pH electrodes. The Nernst response to pH of the sensor is in the range of pH 1-12 with a slope of 60 mV per pH. The sensor has been applied to pH measurements of samples and satisfactory results were obtained with R.S.D. of 0.18-1.25%.