Abstract
Membrane thickness is a very important parameter in controlling the sensitivity of the pH sensor and its other behaviour, such as hysteresis, repeatability, stability and reliability. Therefore, in this research work the thickness of CuS membrane was studied to find its effects on these parameters. CuS membrane was prepared from copper chloride and sodium thiosulfate dissolved in deionized water and ethanol with the ratio (7: 3) then deposited on glass substrates for 60 and 150 sprays, respectively using spray pyrolysis deposition. These thin films were exposed to Xray diffractometer and field emission scanning electron microscopy to recognize their structures and crystal shapes. Then they were used as pH sensors, so their sensitivity, hysteresis, repeatability, stability and reliability were measured. All obtained results confirmed that the membrane with low thickness (sensitivity, linearity and hysteresis 22.9 mV/pH, 93.8%, and 23.75 mV respectively) were much better than that of high thickness (sensitivity, linearity and hysteresis 7.5 mV/pH, 70.2%, and 41.37 mV respectively) as pH sensor.