Detection and Spatial Mapping of Mercury Contamination in Water Samples Using a Smart-Phone

Researchers in UCLA Department of Electrical Engineering have developed a smart-phone based handheld platform that allows for the quantification of mercury(II) ions in water samples with parts per billion (ppb) level of sensitivity.

Long term mercury exposure in the human body by ingesting contaminated water sources could have serious neurotoxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes. Therefore, the detection and quantification of mercury(II) ion contamination in water systems are of paramount importance, and could potentially be used to assist prevention of mercury ions from entering the food chain. Current detection of environmental contamination of trace-level toxic heavy metal ions uses spectroscopic methods such as atomic absorption spectroscopy or atomic fluorescence spectroscopy. These methods rely on complex sample preparation procedures, expensive and bulky instruments, and professionally trained personnel. However, the reality is that on-site detection of contaminants requires portable, rapid, specific, sensitive and cost-effective detection techniques that can be used in resource-limited and field settings.

Researchers in UCLA Department of Electrical Engineering have developed a smart-phone based handheld platform that allows for the quantification of mercury(II) ions in water samples with parts per billion (ppb) level of sensitivity. This is on the same order of magnitude as the maximum contaminant level of mercury(II) recommended for drinking water, as established by the US Environmental Protection Agency and the World Health organization. The device integrates an opto-mechanical attachment to the built-in camera module of a smart-phone to digitally quantify mercury concentration using metal nanoparticle and colorimetric transmission assay that is implemented in disposable test tubes. This sensitive, portable, and cost-effective technology could be useful for distributed sensing, tracking and analysis of global water mercury contamination.

On-site monitoring of heavy metal levels in water samples, specifically mercury(II).

The researchers have built a prototype of the smart-phone based detection platform and demonstrated its functionality by measuring water samples at over 50 locations in California (USA) and generating a comprehensive mercury contamination map. The technology was able to achieve a limit of detection of ~3.5 parts per billion.