Hydrothermal synthesis of TiO2 nanorods as sensing membrane for extended-gate field-effect transistor (EGFET) pH sensing applications

• Titanium-dioxide (TiO 2 ) nanorods were grow on fluorine doped tin oxide (FTO) coated glass substrates via hydrothermal method and influence of hydrochloric acidic (HCL) concentration on the structural form of the synthesized TiO 2 nanorods samples have been investigated. • TiO 2 nanorods based extended gate field effect transistor (EGFET) was fabricated for pH sensing and the sensitivity, linearity, and repeatability of the sensor were examined for pH buffer solutions from 2 to 12. • The sensor exhibits super-Nernstian sensitivity of 78.25 mV/pH and linearity of 99.27 % with a repeatability of 0.23 % and lower hysteresis value of 9.1 mV and the device could be used for the detection of hydrogen ions in various solutions. Titanium dioxide nanorods were prepared by hydrothermal method using titanium tetrachloride TiCl 4 as a precursor solution and an expanded gate field effect transistor's (EGFET) sensing membrane has been used for pH sensing applications. The TiO 2 nanorods were grown onto fluorine-doped tin oxide FTO coated glass substrates at a hydrothermal reaction temperature of 170 °C for 6 h. The effect of precursor solution TiCl 4 and hydrochloric acid HCl concentrations on the crystal form of TiO 2 nanorods was analyzed. The morphology, crystal structures, chemical composition, and the size distribution of the TiO 2 nanorods were characterized by X-ray diffraction (XRD), external field scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM) images. Under strongly acidic conditions, the structural and morphological studies showed that the rutile TiO 2 nanorods shape is the predominant phase. The TiO 2 nanorods sensor exhibited high sensitivity of 78.25 mV / pH and large linearity of 99.27% with good repeatability of 0.23% in a wide sensing range of pH 2–12 with good stability, reliability and showed lower hysteresis value of 9.1 mV. The TiO 2 nanorod pH sensor's high measured sensitivity makes it a feasible contender for a wide range of applications, including pH sensors and biosensors.