Real-time environmental monitoring has the potential to fundamentally reshape how stakeholders detect, track and respond to pollution. As regulatory frameworks tighten, the demand for continuous, high-fidelity environmental data has never been greater. Yet despite advances in analytical chemistry (electrochemical sensing and microfabrication) the field still relies heavily on laboratory-based measurements and periodic sampling.
The gap between aspiration and reality stems from the fact that operating a sensor in the real environment is profoundly different from operating one under controlled laboratory conditions. Natural and industrial environments present a combination of chemical, physical and biological challenges that most sensing technologies were not designed to withstand. For real-time monitoring to become widespread and dependable, these obstacles must be understood at their fundamental level.
Traditionally, colourimetric detection has been used far and wide for environmental testing due to its simplicity and effectiveness in successfully differentiating among volatile organic compounds. However, the technique fundamentally depends on unobstructed optical paths and controlled chemical conditions. These are two things environmental matrices rarely provide.
Turbidity, pigmentation, particulate matter and dissolved organics all interfere with optical readouts. Because of this, colourimetric tests require filtration, chemical preparation or sample extraction. Once those steps are needed, the measurement is no longer real-time and certainly no longer in-situ. The moment a sample must be collected and processed before analysis, the opportunity for continuous monitoring is lost. Simply put, a switch to other sensor types like electrochemical is required to achieve sensing in the field.
A central challenge in real-time monitoring is the sheer variability of environmental matrices. Unlike prepared laboratory samples, real-world samples are not static or homogeneous. Wastewater, stormwater, soil leachate and atmospheric mixtures all contain constantly shifting components that affect sensor behaviour.
For instance, wastewater can change in composition hourly as domestic, industrial and agricultural flows blend. Soil samples contain a mixture of minerals, dissolved gases and microbial metabolites that vary seasonally. On top of this, air mixtures contain particulates, aerosols and volatile organics influenced by weather and human activity.
These fluctuations can have considerable impact on sensor performance, directly altering:
Sensors calibrated in clean water, standard buffers or simplified matrices can easily fail when confronted with these dynamic conditions. Any measurement device intended for continuous environmental use must therefore be capable of functioning in matrices that behave more like a living system than a static sample.
The second major barrier is the universal problem of fouling. Once a sensor is deployed, its surfaces immediately begin to condition to the local environment. This conditioning fundamentally alters the sensor’s electrochemical properties. Biofouling, microbial colonisation and early-stage biofilm formation can dramatically change the sensor’s electrical interface.
Even thin biomolecular layers increase impedance, slow electron transfer and occlude recognition sites. Over longer deployments, biofilms can insulate the electrode completely. Fouling occurs differently in each environment and sensors must be able to withstand it across diverse matrices without constant recalibration or replacement.
A significant barrier to real-time environmental monitoring is the challenge of producing sensors that behave consistently at scale. Environmental monitoring often requires networks of sensors deployed across rivers, treatment works, groundwater systems or catchments, all expected to deliver comparable and stable data over long periods.
Traditional sensing materials make this difficult. Printed carbon inks, carbon nanotube composites and thin metallic coatings (such as gold or platinum films) often show significant batch-to-batch variability. Small differences lead to noticeable changes in baseline noise, sensitivity or drift.
For monitoring networks to function reliably, sensors must be:
The most persistent challenge is that traditional sensor materials were not designed to withstand the environmental conditions described above.
Accurate real-time sensing requires materials that can maintain:
Most commercially used electrodes for electrochemical biosensors (gold, platinum, carbon ink, CNT composites) fail to meet these criteria simultaneously. They excel in the lab, where conditions are controlled, but exhibit drift, fouling, instability or variability when placed into real environments. This material limitation is the primary bottleneck preventing the widespread adoption of real-time monitoring systems.