| Aluminum doped zinc oxide thick films were produced using the sintering method. The powder was prepared by mechanically mixing zinc oxide with Al2O3. The various Al2O3 contents (0%, 1%, 3%, 5%, weight percent) were tested. The powder was calcined at 1100°C for 3h. The paste obtained by mixing the resulting powder with binder and organic solvent was coated on alumina substrate using a doctor blade. The thick films were dried at 100°C for 24h and sintered at 1100°C for 2h.
The sensitivity of the films heated to an operating temperature in a glass tube was measured by the electrical resistance change of the films when the films were exposed to TMA gas or odor from oyster. The operating temperatures were 200, 250, 300, 350 and 400°C, respectively. The concentrations of TMA gas used were 5×10-6, 100×10-6, 150×10-6, 200×10-6 and 300×10-6, respectively. The oyster used for the experiment was stored in a fridge for l, 2 and 3 days, respectively, under a temperature of 5°C.
The results show that the sensitivity increases with an increase in the amount of Al2O3. The temperature at which the films have the highest sensitivity ranges between 350 and 400°C. The sensitivity of the 5% Al2O3 doped zinc oxide thick film to the 200×10-6 concentration TMA gas at 350°C is 47. The response time is about 3 min. The response of 5% Al2O3 doped zinc oxide thick film to the lengths of cold storage time for oyster is sensitive. |
