From Component Supply to Full Sensor Development: Supporting Chloride Monitoring in Concrete with Ag/AgCl Electrodes
Chloride ingress is one of the most significant causes of reinforced concrete degradation. As a result, reliable chloride sensing technologies are increasingly important for infrastructure monitoring, asset management, and durability assessment.
A recent enquiry highlighted a common challenge faced by organisations working in structural monitoring: identifying a supplier capable of manufacturing silver/silver chloride (Ag/AgCl) electrodes suitable for integration into chloride-selective sensors embedded within concrete structures.
The Enquiry
A customer approached a sensor manufacturer after finding a commercially available Ag/AgCl electrode and asked a straightforward question:
Can a supplier manufacture a chloride-selective electrode suitable for embedding in concrete, and what would such a solution cost?
While the request appears relatively simple, the answer depends heavily on the design and requirements of the complete sensing system.
Understanding the Application
The customer's intended application involved measuring chloride concentration in concrete using an ion-selective electrode (ISE) approach.
Silver/silver chloride electrodes are well-established electrochemical components and can be produced in a variety of formats, including:
- Wires
- Filaments
- Pellets
- Rods
- Embedded structures
- Custom geometries
However, electrode manufacture represents only one part of a complete chloride sensing system.
Important design considerations include:
- Reference electrode configuration
- Measurement electronics
- Sensor packaging
- Long-term stability within concrete
- Environmental exposure conditions
- Sensor installation methods
These factors strongly influence the final sensor architecture and electrode design.
Different Levels of Support
One of the key lessons from this discussion is that sensor manufacturers can often support projects at multiple levels depending on the customer's requirements.
1. Component Supply
If the overall sensor architecture is already defined, it may be sufficient to purchase Ag/AgCl electrode materials and integrate them into an existing design.
Ag/AgCl electrodes are available in several configurations depending on the application's mechanical, electrochemical, and manufacturing requirements.
Examples include:
Wire electrodes may be advantageous where flexibility, embedding, or custom geometries are required. Pellet-style electrodes can be attractive for compact sensor assemblies, fixed installations, and integration into custom housings.
This approach is typically suitable when:
- The sensing methodology has already been validated
- The reference electrode has been specified
- The customer has in-house sensor development expertise
- Only sensor components are required rather than a complete sensing solution
2. Prototype and Design Support
Many projects fall between simple component procurement and full product development.
In these cases, support may include:
- Custom electrode geometries
- Packaging and mechanical design
- Protective coatings
- Material selection
- Small-batch manufacturing
- Prototype iteration and optimisation
This approach enables customers to accelerate development while maintaining control of the overall sensing strategy.
3. Full Sensor Development
For novel monitoring applications, a full development programme may be appropriate.
Typical activities include:
- Defining measurement requirements
- Designing and optimising electrode construction
- Evaluating sensor behaviour during concrete curing
- Long-term stability testing
- Environmental validation
- Manufacturing scale-up
Because concrete environments present several unique challenges, thorough validation is often an essential part of the development process.
Why Concrete Applications Are Different
Embedding electrochemical sensors in concrete introduces challenges that are not commonly encountered in laboratory measurements.
These include:
- Highly alkaline environments
- Variations in moisture content
- Chloride transport dynamics
- Mechanical stresses
- Long deployment lifetimes
- Limited access after installation
As a result, expertise in electrochemistry alone is not always sufficient. Successful chloride monitoring projects often require knowledge spanning:
- Electrochemistry
- Materials science
- Civil engineering
- Long-term field validation
Clarifying Requirements Early
One of the key outcomes of the discussion was the importance of defining the overall measurement system before discussing manufacturing costs.
