Feature: Sensors


Still, every sensor system has limitations.


Electrochemical sensors, for example, oſten require regular calibration and maintenance due to driſt. Optical systems can be fouled by microbial growth or particulates, and cleaning them without damaging sensitive components remains a challenge. Sensor lifespan, response time and


accuracy are all dependent on deployment conditions. Moreover, translating raw sensor data into meaningful water quality indicators still requires sophisticated models and validation – particularly when working with complex matrices like estuarine waters or industrial runoff. Portability adds yet another layer


of complexity. Field scientists and environmental engineers need instruments that are not only accurate and robust but also lightweight and easy to deploy, oſten in difficult-to-access locations. Handheld devices, portable colorimeters and miniaturised spectrometers have become increasingly popular in fieldwork, but striking the right balance between portability and performance remains elusive. Smaller systems tend to compromise on analytical power, while more sophisticated systems oſten require bulky peripherals or extensive setup.


Tailored approach Portability is key for water monitoring devices, as testers oſten travel to many different locations. At Hamamatsu, the challenge of portability without sacrificing performance is a driving force behind our sensor design. Our photonic and optoelectronic solutions, particularly those based on advanced spectroscopy, aim to provide highly compact yet sensitive platforms for water quality analysis. Last year we launched a new UV


spectrometer, which is the smallest in the market, just over one fiſth the size of the next nearest alternative. Tis enables it to be fitted into small enclosures, including portable water analysis micro-spectrometer. Te micro-spectrometer’s compact size allows instruments to be customisable for the application rather than relying on a typical standard design. It can be easily mounted in a compact water quality monitor, which can be installed in rivers,


lakes or oceans, enabling close inspection and analysis of many types of pollutants via absorption spectrophotometry. Te device is lightweight and highly sensitive, delivering highly accurate measurements with a spectral resolution of 8nm. Te micro spectrometer analyses in the


UV, giving advantages over other analysis methods, since it is reagent-free and offers real-time measurements. It separates UV light in the range of 190-440nm, and then simultaneously measures the light intensity at each wavelength. Tis doesn’t just identify individual pollutants in water, it also helps to determine their concentrations. It uses a low power CMOS image sensor, covering 300nm over the UV spectral region. With its low power consumption, it is simple to operate the micro spectrometer from battery power alone. It requires only 5V, which means it can be powered with ordinary lithium batteries.


Exciting new frontiers Looking to the future, the field of optical metrology is poised to deliver transformative changes in how we assess water quality. Techniques like hyperspectral imaging, Raman spectroscopy and laser- induced fluorescence are already being adapted for aquatic environments, offering unprecedented sensitivity and selectivity. Hyperspectral systems, for instance, can identify specific algal blooms or organic pollutants based on their unique spectral signatures, providing a powerful tool for early warning systems. Perhaps the most exciting frontier


is the application of quantum imaging technologies. Quantum-enhanced sensors, leveraging the unique properties of entangled photons and quantum correlations, promise to revolutionise the sensitivity and resolution of environmental measurements. Such systems could detect trace pollutants at parts-per-trillion levels or image chemical distributions in situ with extraordinary precision, even in low-light or high-scatter environments. Research is ongoing to make these


quantum technologies compact, cost- effective and robust enough for field


Xenon flash lamp module


Hamamatsu mini spectrometer


deployment. While still largely in the prototype phase, early results suggest they could dramatically outperform current methods in both accuracy and versatility. Hamamatsu is actively engaged in


the development of quantum photonic components that could underpin this next generation of water quality sensors. Our work in low-noise photon detection, high-speed optical sampling and integrated photonic circuits is already feeding into collaborative projects aimed at creating quantum-ready environmental monitoring platforms. Te convergence of photonics, quantum


science and environmental engineering holds the promise of real-time, highly resolved water quality data on a global scale. Ultimately, as demands on water


resources intensify and environmental regulations tighten, the need for accurate, real-time and in situ monitoring will only grow. Te technical challenges are considerable, but so too are the rewards. By harnessing the power of light – from


conventional optics to quantum imaging – we are moving ever closer to the goal of seeing clearly beneath the surface.


www.electronicsworld.co.uk December 2025/January 2026 45


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