Miniature fiber-optic NH3 gas sensor based on Pt nanoparticle-incorporated graphene oxide

A highly sensitive ammonia (NH3) optical fiber sensor is demonstrated using platinum (Pt)-nanoparticle-incorporated graphene oxide (GO). The sensor was fabricated by coating a tapered microfiber multimode interferometer with Pt-decorated GO film. The sensing mechanism of the sensor was based on charge-transfer-induced refractive index changes in the GO: Pt nanoparticles which form an ideal assistant material can improve sensitivity remarkably for gas sensing. The experimental results show a sensitivity of 10.2 pm/ppm with Pt nanoparticles which is three times higher than the sensitivity when coated with pure GO. These results indicate the sensor has the optimal sensing sensitivity when the Pt nanoparticle concentration is 185.2 mg/L and exhibits a linear response with NH3 gas concentration below 80 ppm. This composite film-based passive optical fiber sensor provides an approach for highly sensitive NH3 sensing in a limited space and flammable or explosive environment.