Researchers have developed the most sensitive sensor yet for detecting minute levels of mercury and other heavy metals in our water and fish. IEEE Spectrum reports.
The system currently being used to test for mercury and its very toxic derivative, methyl mercury, is a time-intensive process that costs millions of dollars and can only detect quantities at already toxic levels, according to Bartosz Grzybowski of Northwestern University. “Ours can detect very small amounts, over million times smaller than the state-of-the-art current methods.”
The device is basically a commercial strip of glass covered with a film of ‘hairy’ nanoparticles, like a coat of hair. This “nano-velcro” can then be dipped into water for testing purposes.
- If a metal cation (a positively charged ion) from something like methyl mercury comes in contact with the hairs, the hairs close up around the pollutant, trapping it.
- The film becomes electrically conductive, alerting the tester to the presence of the cation.
- A measurement of the voltage along the nanostructure film indicates the level of contamination.
The nanofilm costs somewhere between $1 to $10 to make, though the device to measure the currents could cost a few hundred.
According to Grzybowski, if you drink polluted water with low levels of mercury every day, it could add up and possibly lead to diseases later on. This system could give consumers the ability to test their home tap water for toxic metals.
The researchers conducted field analyses on water in Lake Michigan near Chicago and on a mosquito fish from the Florida Everglades. The tests of the Lake Michigan water came within the range of the measurements found by the U.S. Food and Drug Administration, and the fish testing was nearly identical to that of the US Geological Survey.
The work was published in Nature Materials last week.