Carbon nanotubes-based optical sensor for hydrogen detection at cryogenic temperature

In this contribution, preliminary results on the capability of Silica Optical Fiber (SOF) sensors, coated by Single-Walled Carbon Nanotubes (SWCNTs) based sensitive material, to perform hydrogen detection at cryogenic temperatures are presented. The optical configuration exploited is the one of a low finesse Fabry-Perot interferometer, with a thin films of SWCNTs deposited onto the distal end of standard optical fibers [1,2]. Changes in the thickness and complex dielectric constant of the sensitive layer as a consequence of its interaction with the analyte molecules lead to changes in the fiber-film reflectance, indicating the presence of hydrogen in the test ambient. Preliminary results obtained from hydrogen detection testing, carried out at a temperature as low as -160 degrees C (113 K), demonstrate the excellent potentiality of the proposed configuration to sense very low percentages of gaseous hydrogen (<5%).