Electrochemical analysis of aluminum IDE sensors for full-spectrum pH detection with theoretical correlation

This study presents the fabrication, chemical preparation, and electrochemical evaluation of an aluminum interdigitated electrode (Al-IDE) sensor for real-time pH monitoring across a full range from pH 2 to 12. Electrical characterization was conducted using current-voltage (I-V) measurements, revealing a distinct V-shaped current response pattern. In acidic conditions (pH 2–7), the current decreased linearly with increasing pH, attributed to the gradual reduction in H⁺ ion mobility and interaction with the electrode surface. Conversely, in alkaline environments (pH 8–12), the current increased markedly with rising pH, especially at pH 11 and 12, due to enhanced OH⁻ ion activity and improved charge transport at the electrode interface. A strong correlation was observed between experimentally measured and theoretically calculated current values, confirming the reliability of the developed calibration models. The close alignment of calculated data with empirical measurements supports the sensor's predictive accuracy. These findings underscore the Al-IDE's sensitivity to ionic fluctuations and validate its effectiveness as a low-cost, CMOS-compatible platform for disposable or portable electrochemical pH sensing applications.