A team of researchers have released a paper detailing a handheld pen-like sensor which changes color when it detects toxic vapors — and that can be relied upon to warn the wielder of everything from spoiled food to nerve gas.
There are a range of gases which are incredibly toxic to human beings, but the list of gases we can reliably detect — through smell or otherwise - before their toxicity becomes a problem is unfortunately lower. The "AIE Handy Pen" is a device which aims to resolve that: A handheld sensor which changes color when exposed to particular toxic gases.
The pen operates through aggregation-induced emission fluorogens (AIEgens), which light up when exposed to particular gases. AIEgens aren't a new concept for gas sensing, but previous efforts have used them in liquid form; the AIE Handy Pen, by contrast, puts them into a needle-like fibre at the end of a handheld pen, making it considerably more portable than previous efforts.
"Thanks to its unique solid-state emission characteristics, the AIEgens can be illuminated upon exposure to gaseous compounds on the fibre, and the fluorescence of the reacted AIEgens could be easily visualized under UV-illumination," the research team explains in the paper's abstract.
"The detection limit could be as low as 3.4 ppb [parts per billion] (for DCP vapors [diethyl chlorophosphite, a nerve gas]) or 0.2 ppm (for amine vapors [produced by rotting food]) with the minimal detection time of 30 min (for DCP vapors) or 5 min (for amine vapors). This AIE pen could be easily expanded by decoration of different kinds of responsive AIEgens for on-site analysis of various toxic vapors."
During testing, the team exposed the amine-sensing pen to salmon which had been refrigerated and compared it to salmon which had been left at room temperature for 48 hours: The pen successfully determined which was which, and returned to its normal color when removed from the area - proving that the sensor is reversible and reusable.
The work has been published in the journal ACS Materials under closed-access terms.