Thin film gas sensors are small, lightweight, and relatively easy to operate; however, the testing of these thin film gas sensors is difficult in harsh environments due to the exposure of critical components to the harsh environment. A need exists for the ability to test thin film gas sensor materials for their response to analytes of interest in a variety of environments, including harsh environments. Currently, a sample holder does not exist that will allow the testing of thin film gas sensor materials in harsh environments. Many of the thin film gas sensors require electrical and mechanical connections in order to operate. Harsh environments tend to degrade many of these connections, compromising sensor performance and shortening sensor lifetime. A sensor holder that provides exposure of the thin film sensor material to the harsh environment, while protecting the electrical and mechanical connections, is needed. The advantages of such a sample holder are that the sensors can be used in a wider range of environments (temperature, humidity, etc.), and a wider range of analytes can be evaluated (hydrazine, ammonia, hydrogen, etc.).
A thin film sensor material sample holder was developed. All components of the holder are made of inert materials, providing excellent resistance to most chemicals. Teflon is widely known for its chemical resistance. Butyl rubber has excellent resistance to many harsh chemicals, including hydrazine, methanol, hydrogen fluoride, acetone, and nitric acid.
The thin film sensor material sample holder is comprised of the following components: two-part Teflon housing (substrate), four Teflon screws, and butyl rubber o-ring. The two-part Teflon housing was designed as follows. The housing was grooved for thin film placement and wire feedthrough. Next, the sample port was designed with butyl rubber o-ring, providing approximately 7.5 cm2 sample area. The two-part Teflon housing is joined using four Teflon screws.
In the current embodiment, the thin film sample is placed in the sample holder, the wire leads are placed in the wire groove, and the two-part housing is joined using the Teflon screws. The sample holder is then attached to a sample chamber with a receptacle matching the sample port on the holder. The sample chamber can be filled with any analyte of interest. The atmosphere in the chamber can be changed at any time, providing the ability to sample a wide variety of environmental conditions (various temperature/humidity/analyte combinations).
This work was done by Tracy Gibson and Steven Parks of ASRC Aerospace for Kennedy Space Center. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact