Online amperometric sensor for low-level hypochlorite detection without electrode fouling

Overview

This project addresses a long-standing challenge in water quality monitoring: the development of a reliable online amperometric sensor for hypochlorite that does not suffer from electrode fouling over extended periods. Hypochlorite is widely used as a disinfectant in water treatment, food processing, and healthcare settings, where maintaining accurate residual chlorine levels is critical for safety and regulatory compliance. Existing amperometric methods for hypochlorite analysis have been available for decades, but fouling of electrode surfaces has limited their usefulness in continuous, online applications. This research seeks to overcome that limitation by designing a compact sensor system capable of operating reliably with sample volumes of 10 cm³ or less.

Technical specifications

The proposed approach builds on the proven maturity of amperometric electronic control systems, as demonstrated in portable glucose analysers. Key technical objectives include:

• Electrode configuration: Identifying a suitable two- or three-electrode setup for stable hypochlorite detection
• Surface modification: Evaluating whether electrode surface modification is required to enhance selectivity and reduce fouling
• Minimal electrolyte operation: Determining the lowest electrolyte concentration at which accurate measurements can be achieved
• Applied potential optimization: Selecting an applied potential that drives hypochlorite reduction while avoiding interference from oxygen reduction
• Cleaning protocol: Incorporating a periodic potential excursion to clean the electrode surface and maintain sensor performance
• Detection sensitivity: Confirming that an adequate amperometric signal can be obtained at concentrations below 0.1 ppm chlorine equivalent

Technology readiness level

The technology is at an early-to-mid research stage. Previous studies have demonstrated that hypochlorite levels at 0.1 ppm can be detected using modified electrochemical cells, various electrode materials, and different electrolytes. These findings provide a strong foundation for developing a fouling-resistant online system. The next phase of validation focuses on systematically identifying the optimal electrode configuration, electrolyte conditions, and applied potentials needed for a compact, fouling-resistant sensor. Successful completion of these validation steps would establish the basis for prototype development and field testing in industrial water monitoring applications.