Simple and effective mercury sensor taps into the power of tapping
Mercury can definitely be harmful in large amounts, and detecting its presence in foods or liquids typically requires lab-based tests. A new nanosensor, however, can quickly detect even tiny concentrations of the heavy metal onsite, simply by tapping on samples.
The prototype device is being developed by a team of scientists from Taiwan's National Tsing Hua University, led by Prof. Zong-Hong Lin.
It utilizes a natural phenomenon called the triboelectric effect, in which certain materials become electrically charged as they move against one another – it's what's responsible for the static charge that occurs when you're combing your hair. More specifically, the nanosensor uses an array of mercury-sensitive tellurium nanowires which build up an electrical charge as they come in and out of contact with mercury ions. Those ions can be present in either foods or liquids.
In the case of the latter, a type of triboelectricity known as solid–liquid contact electrification is at work, wherein a solid material becomes electrically charged by contacting and detaching from an ion-containing liquid.
In a test of the nanosensor, the scientists mounted the device on the finger pad of a robotic hand which repeatedly tapped on the surface of tap and lake water samples, along with samples of mercury-tainted apple, shrimp and spinach. In all cases, the device quickly and accurately detected the samples' mercury levels, which were displayed on the screen of a wirelessly linked smartphone.
It is hoped that once the technology is developed further, it could be used to remotely monitor mercury levels of drinking water sources, or be utilized by health officials in impoverished regions that lack proper testing facilities.
A paper on the research was recently published in the journal ACS Nano.
Source: American Chemical Society