By Gary Thomas
Mercury is one of the toxic ingredients present in effluent discharge from industries which when dumped into water bodies, finds its way into marine life like fish and finally ends up in humans who consume those fish.
Representation of the Nano-Velcro mercury traps (Copyright: Northwestern University)
Existing techniques to monitor mercury levels in water bodies are complex and inexpensive. A collaborative team of researchers from Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and Northwestern University in the US have devised a nanoparticle-based system akin to a nanoscale velcro that can not only detect but also trap toxic materials even at attomolar concentrations.
The focus of the researcher’s experiment was mercury in its most common form known as methyl mercury. The concentration of methyl mercury increases as it goes further up in the food chain. This is why bigger fishes have a higher concentration of mercury. The technology developed by the researchers comprises a glass strip with a film of nanosized hairs. When this apparatus is immersed in water, positively charged ions like mercury and cadmium get trapped between two hairs and the hairs close up. The electricity conducted by the nano-velcro is proportional to the ions trapped in it. Hence, measurement of voltage across the nano-velcro yields the level of mercury present. The added advantage for this technique is the unique property of methyl mercury to get trapped without any other accompanying particles. The technique can be extended to other types of pollutants by modifying the length of the nanoscale hairs. The method is inexpensive as the cost of the glass strip is less than 10dollars while the voltage measuring device will be available for a few hundred dollars. This method facilitates the measurement in the field itself as opposed to conventional techniques where the samples have to be analyzed and measured in a laboratory using expensive equipment.