Volatile organic compound gas detection with a wide concentration range based on optical fiber SPR

This paper proposes a volatile organic compound (VOC) gas sensor based on optical fiber surface plasmon resonance (SPR). The sensor uses a heterogeneous core structure of multimode fiber-single mode fibermultimode fiber, covered by chromium (Cr) film and gold (Au) film to stimulate and spread the SPR, as a transducer. And polydimethylsiloxane (PDMS) is coating to the fiber surface as a VOC-sensitive material. The volume and refractive index changes caused by the reaction of PDMS with VOC gases alter the sensor transmission spectra significantly, which ensures the feasibility of VOC detection by the SPR sensor. According to experimental results, the sensor has outstanding stability for detect isopropanol over a broad concentration range of 0 to 1490 x 103 ppm. In a one-hour and five-days stability test, the sensor's standard error of measurement are 0.0519 and 0.1096, respectively, indicating its good reliability in over the short to long term measurement. The SPR sensor's broad detection range, excellent stability and straightforward fabrication process make it a promising choice for industrial applications.