Mercury can undoubtedly be harmful in large amounts, and detecting the presence of mercury in foods and liquids typically requires lab-based testing. , can quickly detect heavy metals in small concentrations in situ.
The prototype device is being developed by a team of scientists from Taiwan’s National Tsing Hua University, led by Professor Zong-Hong Lin.
It takes advantage of a natural phenomenon called the triboelectric effect. In this phenomenon, certain materials become electrically charged as they move relative to each other. This is the cause of the static electricity that occurs when you comb your hair. More specifically, nanosensors use arrays of mercury-sensitive tellurium nanowires that accumulate charge as they enter and leave mercury ions. These ions can be present in either food or liquids.
In the latter case, a form of triboelectricity is at work, known as solid-liquid contact charging, where a solid material is charged by contact and separation from a liquid containing ions.
To test the nanosensor, scientists attached the device to the finger pads of a robotic hand and repeatedly tapped the surface of samples of tap water and lake water, along with samples of mercury-contaminated apples, shrimp and spinach. In each case, the device quickly and accurately detected the mercury level in the samples and displayed it on the screen of a wirelessly linked smartphone.
Further development of this technology is expected to enable remote monitoring of mercury levels in drinking water sources, as well as use by health authorities in impoverished areas where adequate testing facilities are not available.
A paper on this study was recently published in the journal ACS Nano.
Source: American Chemical Society
