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Innovative Lensless Detection System for Water Quality Monitoring
Researchers have introduced a groundbreaking fluorescence detection system that operates without traditional lenses, offering a highly sensitive means to identify harmful microorganisms in drinking water. This innovative approach holds promise for low-cost and user-friendly monitoring solutions, particularly in resource-challenged regions like developing countries and areas recovering from disasters.
The system’s rapid assessment capabilities could also play a crucial role in situations that demand swift water safety confirmations, such as during swimming competitions—a concern highlighted by recent events surrounding the Paris Olympics.
“Unsafe water supplies account for over a million fatalities each year in developing nations,” emphasized Ashim Dhakal, the research team leader from the Phutung Research Institute in Nepal. “Our goal is to pave the way for simpler, economically viable, and highly effective technologies for assessing drinking water safety, thus saving countless lives globally.”
Traditional methods for evaluating microbial contamination rely on culturing water samples, which can take more than 18 hours. This delay renders these methods impractical for immediate safety assessments, especially in regions lacking adequate skilled personnel, infrastructure, and necessary reagents.
In their publication titled “When a lensless fluorometer outperforms a lensed system” in the journal Optica, the research team, collaborating with institutions from Brazil and the UK, demonstrated that their new fluorometer is capable of detecting fluorescent proteins from bacteria in water at concentrations below one part per billion—all without the use of lenses.
This remarkable sensitivity aligns with the World Health Organization’s standards for identifying fecal contamination in drinking water.
“Conventional fluorometers typically incorporate expensive lenses made from specialized UV-transparent glass, requiring precision in positioning,” Dhakal noted. “Our lens-free design not only significantly cuts costs, size, and weight but enhances performance for monitoring purposes that don’t necessitate imaging.”
Eliminating the Lenses
This research is part of a broader initiative aimed at creating a portable, affordable, and user-friendly device for real-time water quality evaluation. The research team’s investigations revealed that while optical lenses are integral to instruments like cameras and microscopes, they often hinder performance in practical applications where imaging is unnecessary.
“This discovery was pivotal since lenses contribute substantially to the overall expenses of optical systems, and their bulkiness complicates the development of portable devices,” Dhakal explained. “Our findings indicated that optimizing the proximity and size of the light source, detectors, and sample led to a more robust signal, which is essential for effective water quality evaluation.”
Performance Comparison with Lensed Systems
The researchers utilized their insights to design a lensless fluorescence system, deploying large (1–2 mm²) LEDs and detectors now available in UV wavelengths. The setup employs UV light to excite proteins from harmful bacteria, subsequently detecting the emitted fluorescence.
In addition to establishing the sensitivity of the lensless system, the team confirmed that its fluorescence signal is nearly double that of conventional lensed systems. The limited performance of lensed systems is attributed to factors such as numerical aperture constraints and the required distance between components and samples.
Currently, the researchers are developing a compact version of these lensless fluorometers for field testing. They recognize the necessity of validating the device’s resilience across diverse challenging environments before broader application. Moreover, they aim to ensure that the system meets specificity standards for detecting particular bacterial contaminants by integrating multiple measurement parameters.
“Our technology is highly valuable, as it provides sensitive and accurate quantification of bacterial proteins, directly correlating with water treatment efficiency, necessary disinfectant doses, and the potential for bacterial regrowth amid recontamination events,” Dhakal added.
More information: Asim Maharjan et al, Lensless fluorometer outperforms lensed system, Optica (2024). DOI: 10.1364/OPTICA.527289
Citation: Lens-free fluorescence instrument detects deadly microorganisms in drinking water (2024, August 8) retrieved 9 August 2024 from https://phys.org/news/2024-08-lens-free-fluorescence-instrument-deadly.html
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