Electrochemical EGFET pH Sensing Performance using ZnO-based Composite Thin Films Sensing Electrode

Zinc oxide-based composite films extended gate field effect transistor (EGFET) sensing electrode were fabricated on indium tin oxide, ITO substrate using spin coating method. The sensing performance and structural properties of two different structure sensing electrode; bilayer films and composite films were highlighted in this study. The sensitiveness of the sensing electrode was investigated towards different pH buffer solutions within range pH2 to pH12 and semiconductor measuring unit. Here, commercial reference electrode (RE) was used to complete the electrochemical measurement. As a result, the pH sensitivity and linearity value of the bilayer composite was found highest in this study, that is 45.4 mV/pH and 0.9864 respectively. The results can be observed as correlated with the physical properties of the sensing electrodes characterized by field emission scanning electron microscopy and contact angle.