Temperature Self-Calibration of Always-On, Field-Deployed Ion-Selective Electrodes Based on Differential Voltage...

Area of Science:

• Electrochemistry
• Sensor Technology
• Analytical Chemistry

Background:

• Potentiometric ion-selective electrode (ISE) sensors are increasingly used for in situ analyte monitoring in diverse fields like agriculture, environmental science, and healthcare.
• Field applications face accuracy challenges due to uncontrolled temperature variations and infrequent calibration, hindering performance compared to laboratory settings.
• Accurate in situ measurements are crucial for real-time decision-making in environmental monitoring, precision agriculture, and wearable health devices.

Purpose of the Study:

• To develop and validate a novel temperature self-calibration method for potentiometric ion-selective electrode (ISE) sensors.
• To enable accurate, continuous, in situ measurement of analyte concentrations under uncontrolled field conditions by compensating for temperature variations.
• To demonstrate the general applicability of the method for Nernst principle-based sensors in various deployment scenarios, including wearable and implantable devices.

Main Methods:

• Proposed a temperature self-calibration technique where ISE sensors function as integrated thermometers.
• Validated the method using potentiometric pH and nitrate ISEs, leveraging the Nernst principle for electrochemical sensing.
• Conducted controlled experiments with varying analyte concentrations and temperatures, followed by a 6-day field study for continuous nitrate monitoring.

Main Results:

• Achieved high accuracy for pH and nitrate measurements (within 0.3% and 5% of true concentration, respectively) under variable conditions.
• Demonstrated field accuracy within 4% of ground truth for continuous nitrate monitoring over 6 days using the self-calibration method.
• Validated the generalizability of the approach for Nernst principle-based sensors, enabling battery-free, temperature-corrected measurements.

Conclusions:

• The developed temperature self-calibration method significantly enhances the accuracy and reliability of ISE sensors in field applications.
• This approach overcomes key limitations of current in situ sensing, allowing for precise analyte quantification without frequent external calibration.
• The technology holds promise for widespread adoption in environmental, agricultural, and healthcare monitoring, particularly for battery-free wearable and implantable sensors.