Sandia Develops Phase-Change Micro-Valve Sensors

Sandia National Laboratories has developed a miniature phase-change micro-valve sensor for collecting vapor samples. The sensor can be used to collect atmospheric samples, detect gases in industries and battlefields, and sample a person’s breath in point-of-care medicine.

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, Sandia National Laboratories)

The new micro-valve sensor is simple to operate and is inexpensive, tough and light. A commonly used alloy houses a microvalve on top of a sample chamber. The chamber has a tiny hole that captures the gas. The alloy melts and flows upon heating. On cooling it resolidifies and forms an impermeable block that traps the gas sample within the inert chamber. The unique design prevents contamination of the sample till it reaches the laboratory.

The simple design of the sensor allows it to be employed in unmanned aerial vehicles and in atmospheric balloons for collecting climate data worldwide. The inexpensive nature will make it affordable even for poor countries.

Mark Ivey, a researcher at Sandia, is in-charge of the sounding balloon operation in Barrow and Oliktok Point in Alaska for the Department of Energy. The balloons carry sensors into the sky and sample the particles around which the formation of cloud droplets occur. The balloons are connected to winches that are used for reeling back the balloons. In this situation, weight plays an important role and the Sandia sensor holds potential in such applications.

The National Oceanic and Atmospheric Administration and NASA require ground-truth data, and the researchers intend to submit a proposal for atmospheric sampling. The existing systems and containers are heavy and may outgas leading to contamination of the trapped sample.

The Sandia system can have 100 of these devices, equipped with a macrovalve. An altimeter sends a signal for controlling the macrovalve. These miniature samplers may also be used by geoscientists for studying the Earth’s formation and while drilling for oil.

The study was led by Ron Manginell, a researcher at Sandia National Laboratories. The study has been published in AIP’s Review of Scientific Instruments.


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