An air sampler the size of an earplug is expected to cheaply and easily collect atmospheric samples to improve computer climate models. Developed by Sandia National Laboratories, the design employs a commonly used alloy to house an inexpensive microvalve situated above the sample chamber.
When heated, the alloy — a kind of solder — melts and flows, blocking the inlet hole. When cooled, the alloy re-solidifies into an impermeable block that seals the gas sample inside the inert chamber below. Low cost should make widespread distribution of these sensors possible, while the noncontaminating nature of the design helps meet stringent technical requirements.
Better data collection is important because uncertainties in fact-gathering is one reason climate models reach a variety of conclusions. Winds may blow gases toward or away from a sampling site, gas contents at any location may vary by the hour and by the season, and samples collected by containers in the field may evaporate or become corrupted before analysis in a distant laboratory. Compounding the problem are difficulties in widely distributing sensors, which can be heavy, fragile and require expensive tending by humans.
The Sandia phase-change micro-valve sensor is light, cheap, tough, inexpensive to fabricate, and simple to operate. It takes in gas in seconds through a tiny hole about the diameter of three human hairs. The hole closes when a tiny, low-energy hotplate on the canister’s surface melts shut the alloy through which the hole passes, sealing it.
Because the little container doesn’t outgas internally, the trapped sample remains uncorrupted until analyzed in the laboratory. The miniature sensor’s simplicity means it could travel in unmanned aerial vehicles (UAVs) or as unmonitored cargo in atmospheric balloons. Data collected by the tiny cylinders also could be used to confirm satellite images of airborne industrial effluents, essential for monitoring cap-and-trade deals.
But not all potential uses are in the upper atmosphere. Geoscientists drill boreholes for oil and to understand how the Earth formed. The miniature samplers outfitted with microvalves could take samples that can be transported pristinely back to the surface and then examined in a lab.
In medicine, volatile compounds that people and animals emit are indicative of disease states and stress. Point-of-care medicine, instead of taking a blood sample, could sample a person’s breath. Alcohol gives a gross signal, but infections have a high volatile content as well. The bacteria that give cows tuberculosis produce a characteristic signature, for example.
The detector also could be used by the military to collect and analyze gases on the battlefield.