Heater integrated nanopatterned optical fiber-tip to realize a reusable gas sensor

摘要

We present the first heater integrated nanostructured optical fiber of 200 |im diameter to realize a high-sensitivity and reusable fiber-optic gas sensor. In our guided mode resonance-enabled fiber-optic gas sensor, resonance shifts upon the adsorption of the analytes on the graphene oxide (GO) coated sensor surface. For repeated use of this sensor, a regeneration of the sensor surface is required by a complete desorption of the analyte molecules from the GO layer. In our presented design, this has been achieved by the integration of a controllable heater at the fiber tip. The heater was fabricated by embedding a helical thin nichrome wire wrapped along a cylindrical rod into a precursor solution of polydimethylsiloxane, and subsequently removing the rod from the cured elastomer and leaving the helical wire inside the elastomer. Thus, a cylindrical cavity of length 16 mm and diameter 4 mm surrounded by the helical wire was formed that then contains the fiber-tip sensor. For the ethylene gas analyte, we demonstrated the reversibility of the heater integrated fiber-tip sensor, with a tunable recovery time. Owing to the rapid heat transfer from the helical wire to the encased fiber-tip sensor, the heater integrated fiber-tip sensor responds to heating in only about 2.5 min. The high resonance sensitivity of the nanopatterned fiber-tip to its surrounding refractive index, in conjunction with excellent repeatability through integrated heating for surface regeneration, enables a practical fiber-tip based remote sensing.