High Performance EGFET-Based pH Sensor Utilizing Low-Cost Industrial-Grade Touch Panel Film as the Gate Structure

This paper develops a high performance extended-gate field-effect-transistor-based pH sensor utilizing industrial-grade touch panel film (TPF) as the sensing material. The TPF is composed of a polyethylene terephthalate substrate coated with an indium tin oxide, a silicon dioxide, and a niobium pentoxide (ITO/SiO₂/Nb₂o₅) layers. Since industrial roll-to-roll process is used to produce the TPF such that the cost and the quality for the film are very competitive for producing disposable sensors. Results show the developed sensor exhibits high sensitivity of 59.2 mV/pH in the range of pH from 3 to 13 with a good linearity of . It also shows excellent sensing performance including ultrafast response ( s), good repeatability (variation %), and stability (variation %). When interfered with high concentration Na⁺ ions (0.1 M) by adding normal saline water, the response increases slightly and sustain linearity. In addition, the performance of the developed sensor owing to sensing area change is evaluated that presents good linearity and consistent in the sensing areas range mm². Accordingly, the developed TPF-based pH sensor has presented its potentials for rapid and low-cost hydrogen ion detections.