Development of an EGFET pH sensor using tio2-pani composite thin films for soil characterization

Regular pH soil testing is needed to ensure soil health and improve crop yield. This can be done through laboratory testing or utilizing a commercially available sensor. The soil lab test was unappealing due to inconvenient soil sampling procedures and a high cost. Commercial soil sensors, however, are an undesirable method due to their poor precision and reliability. Thus, this study aims to develop an effective and reliable soil sensor using a highly sensitive extended gate field effect transistor (EGFET) pH sensor based on TiO2-PANI composite thin film. The deposited sample was tested for pH application in the range of pH 2 to 12. The sample demonstrated a super-Nernstian behavior with 66.1 mV/pH and a linearity of 0.9931. Additional testing revealed that the sample exhibited good repeatability with a standard deviation of 0.49%, and a low drift rate of 4.96, 5.54 and 3.32 mV/h in pH 4, 7 and 10, respectively for 6 hours, indicating that the sample is stable in the long term. Besides, the laboratory test and direct characterization via soil EGFET measurements were compared. The results show that the fabricated TiO2-PANI composite thin film in this work is beneficial for soil testing