The sensors are fabricated with optimal L/W ratio at 4 to explore their responses to pH changes. The samples was prepared with pH values of 3, 5, 7, 9, 10 and incubated with individual sensors to investigate the pH response. The initial resistances were recorded as a wet channel incubated with pH7 (primed with the neutral point) before other sample incubation. Then the sensor was dried in ambient for 6 hrs to recover its dry R.