Titanium Nitride Thin Film Based Low-Redox-Interference Potentiometric pH Sensing Electrodes

Area of Science:

• Electrochemistry
• Materials Science
• Sensor Technology

Background:

• Developing robust potentiometric pH sensors is crucial for analyzing complex samples.
• Existing sensors often face challenges with stability and interference in matrices like juices and wine.
• Titanium Nitride (TiN) is explored as a potential working electrode material for improved sensor performance.

Purpose of the Study:

• To design and characterize a novel solid-state potentiometric pH sensor utilizing a Radio Frequency Magnetron Sputtered Titanium Nitride (RFMS TiN) working electrode.
• To evaluate the sensor's performance, including linearity, hysteresis, and drift.
• To compare the redox interference performance of TiN electrodes against Iridium Oxide (IrO2) electrodes.

Main Methods:

• Fabrication of a solid-state potentiometric pH sensor with an RFMS TiN thin film working electrode.
• Utilizing a commercial Ag|AgCl|KCl double junction reference electrode.
• Testing sensor performance metrics: pH slope, linearity (R^2), hysteresis, and drift.
• Assessing redox interference using ascorbic acid (reducing agent) and comparing TiN with IrO2 electrodes.

Main Results:

• The TiN-based sensor exhibited a linear pH slope of -59.1 mV/pH with R^2 = 0.9997.
• Achieved low hysteresis (1.2 mV) and drift (< 3.9 mV/hr), indicating high stability.
• TiN electrodes showed significantly less potential shift (-32 mV) in ascorbic acid compared to IrO2 electrodes (-114 mV).

Conclusions:

• The developed RFMS TiN solid-state pH sensor offers excellent performance characteristics, including linearity and stability.
• TiN electrodes demonstrate superior resistance to redox interference compared to IrO2, making them suitable for difficult matrices.
• This technology holds promise for miniaturized, cost-effective, and robust pH sensing in challenging applications like wine and fresh juice analysis.