Highly sensitive ion-sensitive field-effect transistor sensor using fully transparent amorphous In–Ga–Zn–O thin-film transistors

In this study, a highly sensitive ion-sensitive field-effect transistor (ISFET) sensor was developed using fully transparent amorphous In–Ga–Zn–O thin-film transistors fabricated on a glass substrate. To overcome the issues associated with conventional ISFETs, such as low sensitivity and poor reliability, a dual-gate (DG) operating mode was employed, which is able to significantly amplify the sensitivity through capacitive coupling between the front and back gate dielectrics. As a result, when compared to the sensitivity in the single-gate mode, the DG mode exhibited a high sensitivity of 269.3 mV/pH, which is beyond the Nernst response limit.