Influence of NH₃ plasma and Ti doping on pH-sensitive CeO₂ electrolyte-insulator-semiconductor biosensors

In this study, CeO₂ pH-sensitive sensing membranes in electrolyte-insulator-semiconductor structures on silicon substrate were fabricated. To enhance sensing performance, the membrane underwent Ti doping and NH₃ plasma treatment on the surface. To examine the effects of Ti doping and plasma treatment, multiple material properties evaluations were conducted using field-emission scanning electron microscopy, X-ray diffraction, atomic force microscopy, and secondary ion mass spectroscopy. Results indicate that Ti doping and plasma treatment can remove defects and enhance crystallization, thereby achieving improved pH-sensing performance of the membrane with high sensitivity, high linearity, low hysteresis voltage and low drift voltage. CeO₂-based EIS membranes with Ti doping and NH₃ plasma treatment show promise for future portable pH-sensitive biosensors.