Amorphous ZnSnxOy Fabricated at Room-Temperature for Flexible pH-EGFET Sensor

In this article, the zinc-tin oxide (ZnSn
_x
O
_y
) based sensing membrane fabricated on a flexible polyethylene terephthalate substrate at room temperature as an extended-gate field-effect transistor (EGFET) is investigated for pH-sensing applications. The ZnSn
_x
O
_y
-based EGFET sensor showed a super-Nernstian pH response (70.79 mV/pH) with very good linearity (0.997), a low hysteresis voltage (6 mV), and a low drift rate (0.25 mV/h). The high pH sensing behavior is attributed to the redox reaction of amphoteric zinc oxide (ZnO) in different pH solutions. Furthermore, good flexibility and bendability were shown by the ZnSn
_x
O
_y
-based EGFET sensor after 400 bending cycles.