Chennai: Nano-sized copper balls that emit red luminescence, developed by IIT Madras researchers, can be used as sensors that can detect even extremely low concentrations of arsenic pollution in water.

Researchers at the Centre of Excellence (CoE) for molecular material and functions at IIT-M, who have developed the light emitting material, will eventually develop a device that can instantly detect arsenic contamination in water.

T Pradeep, head of the CoE, said small spheres of molecular copper (18 copper atoms form a molecule) that together have a characteristic property to emit red light were assembled. When interacting with arsenate and arsenite, which are arsenic compounds, in water, the balls of copper break and the emitted red light disappears.

This helps detect the presence and quantity of arsenic in water. "We have applied for a patent for this process, which can be made into any device. What we have thought about is a mobile phone-like device that can read the fluorescence and the analytics built on the cloud will tell you how much the concentration is. We already have a similar device for fluoride and some other contaminants," said Prof Pradeep. The key is that it can detect even as low as one part per billion. The limit of arsenic in drinking water is 10 parts per billion. The sensor also selectively identifies arsenic in the presence of other common metal ions like cadmium, mercury, iron, lead, copper, and chromium, he added.

Jenifer Shantha Kumar, research scholar at the CoE, said the cost of one water quality test using this sensor was estimated to be approximately 1. The centre is a collective of 25 Indian and foreign faculty members including nine from IIT-M. Researchers said the industries that would benefit from the research from the centre include those on sensing, catalysis, energy, carbon dioxide sequestration and sustainability.