Feature: Sensors
New developments in multi- parametric sensor systems
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By Craige Palmer, Sales Director, Hamamatsu Photonics UK Add to that the remoteness or
easuring water quality in situ, i.e., directly at the source – be it a fast-flowing river, a tranquil lake,
a vast reservoir, or the shiſting tides of the ocean – has long been a technical challenge. While laboratory analysis allows for precise testing under controlled conditions, in situ monitoring demands technology that can deliver reliable, real-time data in environments that are anything but controlled. Tis is no small task. One of the most
persistent technical challenges in in-situ measurement lies in the sheer variability of aquatic environments. Water chemistry is easily affected by variable temperature, pressure, salinity, turbidity and biological activity, all of which influence readings and can disrupt them. In rivers, rapid changes in flow and sediment load can alter readings and damage delicate sensor components. In lakes and reservoirs, stratification
– layering of water due to temperature differences – complicates the picture, requiring measurements at multiple depths to obtain a representative snapshot. Sensors must therefore be rugged enough to withstand these conditions while maintaining calibration and sensitivity over time.
inaccessibility of many of these water environments, and it becomes clear why the measurement of water quality remains one of the most demanding areas in environmental science. Another key difficulty in in-
situ measurements is selectivity. Many conventional sensors rely on electrochemical principles, such as ion- selective electrodes or amperometric techniques, which can suffer from cross- sensitivity to other substances in the water. For instance, detecting low concentrations
of nutrients like phosphates or nitrates is critical in monitoring eutrophication, but sensors must distinguish these from similar ions or background noise. Optical techniques such as fluorescence
and absorbance spectroscopy have been deployed to improve selectivity, but they bring their own challenges, such as sensitivity to turbidity or the need for precise alignment of optical paths, something not easily guaranteed in rough field conditions.
Multi-parametric systems Despite these hurdles, progress has been substantial, as engineers develop in- situ sensor systems that can detect key
44 December 2025/January 2026
www.electronicsworld.co.uk
parameters such as pH, dissolved oxygen, turbidity, nitrates, heavy metals and biological contaminants. Today, in-situ sensor platforms increasingly incorporate multi-parametric systems – suites of sensors embedded in a single unit, capable of measuring a wide range of indicators simultaneously. Tese platforms are oſten integrated in autonomous buoys, drones or underwater vehicles, and can be deployed for weeks or months, transmitting data in real time via satellite or cellular networks. Power efficiency, data processing and sensor miniaturisation have all improved significantly, enabling longer deployment times and greater data resolution. One important device used in monitoring
water quality is the xenon (Xe) flashlamp. Tis is a pulsed light source that gives an instantaneous high peak output and has many advantages over other light sources, including its small size, low heat generation, easy handling and a continuous spectrum from UV to IR (160-7500nm). Such a device is filled with very pure xenon gas in a small enclosure that contains an anode and cathode. Te broad spectrum of xenon flashlamps can be harnessed to measure phosphorus, total nitrogen and other chemicals by absorption and fluorescence spectroscopy.
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