26 May 2011 Monitoring organic volatiles and flammable gases with a holographic sensor
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There is an increasing preoccupation regarding the effects of organic volatiles or explosive gases in human welfare and society. A holographic sensor for gaseous and volatile compounds was produced by diffusion of silver salts in a silicon elastomer (PDMS). The salts were reduced to produce silver particles, which upon ablation with a pulsed laser form fringes of nano-sized silver grains. The fringes are separated by about half of the wavelength of the laser (266nm) producing a photonic effect that can be measured as a colorful reflection. A CCD spectrophotometer was used to detect the reflected wavelength of the hologram illuminated with a white light source. The molecular affinity of PDMS for organic molecules can be expressed as intermolecular forces in terms of the cohesive energy density. This parameter is used to predict with great accuracy the sensor performance. Hydrocarbon gases at different concentrations were tested for 3 sets of temperatures. Alkanes, alkenes and alkynes containing 2 to 4 carbon atoms were detected. The sensor responds in less than 5s to the hydrocarbon gas presence in a range of concentrations from 0% to 100% (v/v). Liquid organic compounds exhibit a slower response; however, the results agree with the prediction imposed by the cohesive energy densities. The capabilities of the sensor make it ideal for applications in indoor environment monitoring or dangerous environments enriched with such organic compounds.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. L. Martínez-Hurtado, J. L. Martínez-Hurtado, C. A. B. Davidson, C. A. B. Davidson, C. R. Lowe, C. R. Lowe, } "Monitoring organic volatiles and flammable gases with a holographic sensor", Proc. SPIE 8024, Advanced Environmental, Chemical, and Biological Sensing Technologies VIII, 80240Y (26 May 2011); doi: 10.1117/12.887295; https://doi.org/10.1117/12.887295

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