Anion sensing and interfering behaviors of electrolyte-insulator-semiconductor sensors with nitrogen plasma-treated samarium oxide

In this article, we demonstrate a samarium oxide (Sm₂O₃) electrolyte-insulator-semiconductor (EIS) sensor with nitrogen plasma immersion ion implantation (PIII) treatment for anion sensing and interfering characterization. Chloride (Cl^-), nitrite (NO₂^-), and nitrate (NO₃^-) ions were detected, and the sensitivity was about 49.75mV/pCl, 53.8mV/pNO2, and 56.19mV/pNO3, respectively. Ion sensitivity was enhanced with the increase in ionic radius of the target ion. Titration was performed to analyze the interference of anions. To assess interferences from these ions (Cl^-, NO₂^-, and NO₃^- selectivity coefficients obtained by fixed interference method (FIM) measurements were presented. In result, the coefficients indicate that the interference can be ignored. Furthermore, characteristics of drift demonstrates that the sample exhibits long-term stability for significantly lower drift of chloride, nitrite, and nitrate ions, respectively. The Sm₂O₃ EIS sensor with nitrogen PIII treatment exhibits superior anion sensitivity, selectivity, and stability; therefore, this sensor is suitable for future biosensing applications.