Leaky-waveguide-conversion-type POF alkane-gas sensor using carbon-black dye

We study a leaky-waveguide-converted plastic optical fiber (POF) alkane-gas sensor using polyisoprene as the cladding, which swells in the presence of alkanes. The proposed sensor has a two-layered structure with a light-absorbing layer on the swollen cladding to improve the sensor sensitivity. The upper-layer of the double-layered sensor is formed through the Electrospray Deposition (ESD) method, which enables thin-film formation in a dry process. In the ESD method, high-voltage is applied to a liquid, and the subsequent evaporation and splitting of the droplets is used to form a thin film. However, due to high-voltage application, antistatic treatment is essential for the POF. Therefore, tributylmethylammonium-bis is added to the lower layer and carbon black to the upper layer for providing conductivity. As a result, a sensor with a two-layered structure using carbon black is fabricated with improved sensitivity.