In this thesis, the effect of the synthesis method of polyaniline (PANI) thin films on their morphology an‎d performance as potentiometric pH sensors has been studied. In this work, polyaniline thin films were synthesized by three different methods i.e., potentiostatic method (performed by applying a constant potential for three different times i.e., 100, 200 an‎d 300 seconds), galvanostatic method (performed by applying a constant current for three different times i.e., 100, 200 an‎d 300 seconds), an‎d cyclic voltammetry (using the cyclic potential at three different scan rates i.e., 0.1, 0.075 an‎d 0.05 V/s) on glassy carbon electrodes (GCEs) as active substrates. Also, four different common acids i.e., hydrochloric acid, sulfuric acid, perchloric acid, an‎d phosphoric acid were used as dopants. Polyaniline modified glassy carbon electrodes (PANI/GCEs) were tested as pH sensors using different solutions, ranging from pH 1.5 to 12.5, by measuring the open circuit potential to obtain the the calibration curve, correlation coefficient, accuracy, repeatability, an‎d response time, an‎d the results were compared to find the most optimal sensor. The fabricated sensor by galvanostatic method for 100 seconds in sulfuric acid, with a calibration sensitivity of 74.44 mV/pH is the most optimal sensor. This sensor has a response time of less than 5 seconds an‎d excellent accuracy an‎d repeatability. Finally, as a supplementary work, the synthesis conditions of this sensor were used in the fabrication of a polyaniline-based wearable sensor for measuring the pH of human sweat. This sensor consists of a graphite electrode modified with polyaniline an‎d a printed silver electrode as a reference electrode. The developed wearable sensor presented a sensitivity of 71.22 mV/pH in the pH range of 2 to 9. This result indicates that the sensor has maintained Super-Nernstian sensitivity. This sensor was used to measure the pH of an artificial sweat sample an‎d the results were compared with the results of a commercial pH meter.

اسماعيل حيدري

محمد ديناري

محمدمحسن مومني هامانه , كيومرث زرگوش