Plate Nº 18 · recorded November 14, 2026
Chemistry & MaterialsReported finding
Turkish Chemists Build a Mercury Sensor a Phone Camera Can Read
A selenium-based sensor from Istanbul Technical University detects mercury(II) in seconds, reads out via color change or a Redmi Note 10S camera, and works in water, food and cells.
By James Calloway4 min read717 words
In brief
- ITU's NIR-2 sensor detects mercury(II) down to 3.77 × 10⁻¹⁰ M by UV–visible spectroscopy, below the EPA's 2 ppb drinking-water limit.
- The sensor turns yellow to green and emits near-infrared light within about 10 seconds, staying stable for at least 20 minutes.
- A Redmi Note 10S smartphone measured mercury from 1.66 × 10⁻⁹ to 7.50 × 10⁻⁶ M — the most sensitive phone-based range reported so far, per the authors.
- NIR-2 was tested in water, fruits, grains, legumes and three human lung cell lines, with cell viability above 90%.
- The study appears in Talanta (2026), DOI: 10.1016/j.talanta.2026.129679.
A single molecule developed at Istanbul Technical University can flag mercury(II) ions at concentrations as low as 3.77 × 10⁻¹⁰ moles per liter — a level far below the U.S. EPA's drinking-water limit of 2 parts per billion. When mercury shows up, the sensor flips from yellow to green and emits near-infrared light within roughly 10 seconds.
The research, led by Dila Cetin and colleagues and published in the journal Talanta, addresses a stubborn practical problem: mercury contamination is invisible. A glass of water or a strawberry carrying trace amounts of the toxic metal looks exactly like a clean one. Detecting those traces normally demands specialized lab equipment and trained hands.
How does one molecule ring the alarm?
The sensor, called NIR-2, works like a tiny warning light that stays off until mercury arrives. At its heart sits a selenium-based molecule locked in a closed form that emits almost no light. Mercury(II) ions strongly attract selenium. When one grabs the sensor, it pulls the molecular lock open.
That small structural change produces two readable signals at once: a visible color shift and intense near-infrared fluorescence. The color change can be seen with the naked eye or captured by a camera. The near-infrared signal can be read with lab instruments and, the researchers showed, used for imaging inside living cells.
"Our goal is not simply to detect smaller amounts of mercury(II) ions, but to make that detection easier to see and potentially easier to perform outside a specialized laboratory," said Ismail Yilmaz, a professor in ITU's Department of Chemistry. "A sensor that produces several readable signals gives us more options for how and where mercury could eventually be monitored."
What does this change for actual testing?
The researchers pushed the idea toward cheap hardware. They photographed sensor samples with a Redmi Note 10S smartphone and analyzed the ratio of red to green pixel values, which reduced the distortion from varying lighting. That phone-camera method detected mercury(II) across a range from 1.66 × 10⁻⁹ to 7.50 × 10⁻⁶ M. The authors call it the most sensitive smartphone-based Hg²⁺ detection range reported so far — a claim about their own literature, and one that independent replication has not yet tested.
The spectroscopy numbers are stronger still. UV–visible spectroscopy reached a detection limit of 3.77 × 10⁻¹⁰ M, while fluorescence measurements reached 4.54 × 10⁻⁹ M. The response stayed stable for at least 20 minutes.
The team went beyond clean lab solutions. They tested the sensor in drinking water, tap water and lake water, plus strawberries, watermelon and cherries — all spiked with known mercury amounts to check accuracy. In rice, corn, beans and lentils, the visible color change gave semiquantitative answers, though performance varied across the different food matrices.
They also ran NIR-2 in three human lung cell lines. Cell viability stayed above 90 percent, and fluorescence imaging confirmed a mercury-dependent signal inside the cells. Impressive, but early.
What are the caveats?
Plenty, and the study's own authors acknowledge them. Sample preparation was still required. Measurements relied on controlled lighting. Most experiments used samples the researchers themselves spiked with mercury, rather than naturally contaminated ones. Before NIR-2 becomes anything resembling a consumer detector, it needs field testing across real environmental conditions and genuinely dirty samples.
The realistic payoff may not be replacing analytical labs at all. It's moving sensitive chemistry closer to where contamination happens. Today the routine is slow: collect a sample, ship it to a lab, wait for results from expensive equipment. A molecule that reacts in seconds and offers multiple readouts could shrink that pipeline.
The researchers also suggest the selenium-switch design could serve as a template for sensors targeting other substances. That's a proposal, not a result.
A glass of water laced with trace mercury still looks like clean water. NIR-2 doesn't make the mercury visible — it makes the mercury measurable. Whether that measurement survives contact with the real world is the next experiment.
Dila Cetin et al., "A novel near-infrared-emitting selenolactone-cyanine chemosensor platform for ultra-trace mercury(II) detection in environmental, food and living cell samples," Talanta (2026). DOI: 10.1016/j.talanta.2026.129679
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Staff writer covering regulation, policy and their impact on general science news at SciBeat.
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