Investigation of cellulose and tin oxide hybrid composite as a disposable pH sensor

This paper reports a low cost and disposable pH sensor made with a cellulose and tin oxide hybrid composite. Cellulosetin oxide hybrid composite was prepared by wet chemical method, which involves immersion of a wet regenerated cellulose film in to a mixture of deionized water and SnF ₂ (5 mM concentration), maintained at 90°C for a given time; 6, 12, 18 and 24 h with stirring. The proposed pH sensor showed a consistent increase of its conductance, and the sensitivity defined as the change of resistance with respect to the pH level portrays three regions with different slope rates depending on the pH value: 0.4 MΩ/pH, 31.2 kΩ/pH and 0.2 MΩ/pH in pH range of 1-4, 4-8 and 8-12, respectively. The high sensitivity at the pH range of 4-8 is very useful for industrial applications. Also, Since the proposed pH sensor is made with cellulose film, it is disposable, cheap and environment-friendly.