Air-quality monitoring can be a tricky business. Gasses may be blown into the sampling site from another area, they may leak out of an air sample before it can be analyzed, or the sampling container itself may introduce compounds, emitted through off-gassing. If samples are being gathered in remote areas, it can also be difficult getting bulky equipment to and from the sampling site. Now, scientists from Sandia National Laboratories have announced a tiny new type of air sampler, that addresses these and other challenges.
Sandia ear-plug-sized samplers, with silvery microvalves and solder connectors, seemingly hang poised to sample gases relevant to climate and weather. The prototype devices actually rest on a mirror, reflecting the day’s Albuquerque weather. (Photo by Randy Montoya)
Each sampling container is only about the size of an earplug, and incorporates a chamber made from commonly available alumina alloy, that is topped with a tough, inexpensive microvalve. An electric pulse (provided by an external source) causes that valve to open, drawing the necessary volume of air into the chamber within a few seconds, through an opening with a diameter close to that of three human hairs.
A tiny hotplate built into the top of the chamber then heats the alloy adjacent to that opening. Because alumina is a type of solder, it liquefies, filling in the opening. Once the melted solder cools and resolidifies, the air is sealed inside the chamber. It can stay in there indefinitely, until the sampler is opened at a laboratory for analysis. The alloy doesn’t off-gas at all, so the sample inside the chamber should remain uncorrupted.
Read the rest of the article and analysis at Product Design and Development, Azosensors.com (the A to Z of sensors), bits of science, or gizmag.com. Read the Sandia news release. Sandia news media contact: Neal Singer, 505-845-7078.