When developing a pH sensing product, engineers often focus first on analytical performance. Questions around accuracy, stability, calibration, drift and lifetime are all important. However, as products move from concept to deployment, commercial considerations can become just as important as technical performance.
Recently, we worked with a customer who was evaluating pH sensing technologies for a future soil monitoring product. Their initial direction was based on ISFET pH sensors, a well-established technology that offers several advantages in certain applications. However, during development they encountered a combination of technical and commercial challenges that led them to evaluate alternative approaches.
Ultimately, they chose to investigate Zimmer & Peacock's printed electrochemical pH sensor platform.
This article discusses some of the factors that can influence that type of decision.
The Growing Need for Soil pH Monitoring
Soil pH plays a critical role in agriculture because it influences nutrient availability, fertiliser efficiency and overall crop performance.
As agriculture becomes increasingly data-driven, developers are exploring portable and connected systems capable of helping growers understand soil chemistry more frequently and at lower cost.
However, soil measurement creates unique challenges:
- Sensors may be deployed outdoors.
- Measurement environments can vary significantly.
- Sensors may encounter dirt, moisture and contamination.
- Large numbers of measurements may be required across multiple locations.
- Consumables may need periodic replacement.
These practical considerations mean that developers must think not only about measurement performance but also about sensor replacement, maintenance and long-term economics.
The Challenge with Scaling Sensor Technologies
Many sensing projects begin with a small number of devices.
At the proof-of-concept stage, purchasing a handful of sensors often represents only a small fraction of overall development costs. As a result, the unit cost of the sensing element may not initially appear important.
The situation changes dramatically when planning for:
- Pilot deployments
- Customer evaluations
- Limited commercial releases
- Large-scale agricultural deployments
- Consumer-facing products
At these stages, sensor pricing begins to have a direct impact on product economics.
In the case of the soil-monitoring developer discussed here, the question was not simply whether a sensor could measure pH. The question was whether the sensing approach could ultimately support deployment at commercially meaningful volumes while maintaining an attractive cost structure.
Technical Considerations in Soil Applications
Soil measurement is often more complicated than laboratory measurement.
Developers must decide whether measurements will be performed:
- Directly in soil
- In extracted soil pore water
- In soil-water slurries
- Through periodic spot testing
- Through permanently deployed probes
Each approach introduces different challenges relating to calibration, contamination, maintenance and measurement repeatability.
As a result, application-specific validation becomes essential.
No sensor supplier can fully characterise every soil type, fertiliser regime, irrigation strategy or agricultural environment. Performance must ultimately be validated within the intended use case.
For this reason, we encourage organisations to evaluate sensors using their own soil samples, workflows and operating procedures.
Why Printed Electrochemical Sensors Can Be Attractive
Printed electrochemical sensors offer several characteristics that can make them attractive for soil-monitoring products:
- Low-profile form factors
- Disposable or replaceable sensor concepts
- Scalable manufacturing
- Integration into cartridges and accessories
- Lower cost pathways at higher volumes
- Simplified replacement strategies when sensors become contaminated
For some developers, the ability to replace a sensing element can be particularly attractive in agricultural environments where exposure to soil, fertilisers and organic matter can place significant demands on sensing systems.
Understanding Volume Economics
One reason we published our article on pH sensor pricing was that many organisations struggle to estimate how sensor costs evolve during product development:
The article was inspired in part by discussions with a customer evaluating pH sensing technologies for a commercial product. While technical considerations played an important role in their decision-making process, the commercial outlook was equally important.
As projected deployment volumes increased, the economics of the sensing solution became a significant factor. This prompted the customer to explore alternative technologies that could offer a more attractive path to scale.
For any organisation developing agricultural sensing products, it is worth considering not only what a sensing platform costs today, but what it may cost when thousands or tens of thousands of sensors are required annually.
The Importance of Early Evaluation
Before considering production volumes, developers should first establish whether the sensing technology works within their intended use case.
Questions such as:
- Measurement accuracy
- Sensor lifetime
- Calibration requirements
- Storage requirements
- Soil-to-soil variability
- Environmental robustness
- User workflow
can only be answered through application-specific testing.
For this reason, many developers begin with evaluation kits containing:
- Sensors
- Electronics
- Calibration solutions
- Application guidance
This allows performance to be assessed under real operating conditions before committing to a particular sensing strategy.
Technical Validation Remains Essential
It is important to recognise that no sensor supplier can completely characterise performance in every soil-monitoring application.
Factors such as:
- Soil composition
- Moisture content
- Fertiliser usage
- Temperature
- Measurement frequency
- Sensor cleaning procedures
- User handling
can all influence performance.
Successful product development therefore requires application-specific validation regardless of whether the selected technology is based on ISFETs, glass electrodes or printed electrochemical sensors.
Moving from Development to Commercialisation
The customer described in this article ultimately concluded that printed electrochemical pH sensors were worth evaluating because they offered both a technically viable path and a potentially more favourable commercial pathway at scale.
Their experience highlights an important lesson for agricultural technology developers:
The best sensing technology is not necessarily the one with the most impressive technical specification. The best sensing technology is often the one that successfully balances performance, maintainability, scalability and commercial viability.
Learn More
pH Hyper Value Sensor Datasheet
https://shop.zimmerpeacock.com/cdn/shop/files/TDS_Sensor_pH_hyp.pdf?v=5647440510647422541