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Gas-sensitive holographic sensors


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Date: 2013-04-16

Awarding Institution: University of Cambridge

Author Affiliation: Department of Chemical Engineering and Biotechnology

Institute of Biotechnology

Qualification: PhD

Language: English

Type: Thesis

Metadata: Show full item record

Citation: Martínez Hurtado, J. L. (2013). Gas-sensitive holographic sensors (doctoral thesis).

Description: Sensors for volatile organic compounds (VOC) and hydrocarbons made by photonic gratings in PDMS (poly dimethylsiloxane). Sensors for Ammonia and Oxygen attempted using Nafion membranes.

Abstract: Holographic sensors are photonic layered structures contained in analyte sensitive lms that upon illumination produce monochromatic reflections (λ). The present work reports the fabrication of oxygen and ammonia sensors in Nafi on membranes and hydrocarbon and volatile organic compound sensors in poly(dimethylsiloxane) (PDMS) films. A holographic recording technique was developed to suit these materials consisting of the in situ formation of nanoparticles of 18nm average diameter and their subsequent ordered ablation with a 300mJ laser. The wavelength of the monochromatic reflections depends principally on the refractive index of the resulting layers (n) and the separation between them (Λ). Changes in these parameters are generated by the analyte-sensor interactions and their magnitude can be correlated to the analyte concentration. The strength of these interactions is determined by the thermodynamic properties of the analytes, such as the cohesive energy density (δ^2), and this, was coupled with a photonic model for the prediction of the holographic response. After exposure to different concentrations of the analytes, the kinetics of the responses were determined and the lowest detection limits (LDL) established as follows: Hydrocarbons in PDMS holograms 1% (v/v) in 3s for a range of concentrations from 0-100%; ammonia in Nafi on holograms 0.16% in 100s in the 0-12.5% range; the LDL for oxygen sensing could not be determined although the response was recorded down to 12.5% and up to 100% in 100s. Holographic sensors show competitive responses comparable to commercially available gas sensors for biomedical diagnostics and industrial process monitoring because of their facile fabrication and their shared sensing platform allowing multiplexing.

Keywords: Gas, Sensing, Photonic, Grating, Holographic, Sensor, PDMS, VOC, Hydrocarbons, Nafion, Oxygen, Ammonia

Sponsorship: The student was supported by the Mexican National Council for Science and Technology CONACYT [grant 182820].

Identifiers:

This record's URL: http://www.dspace.cam.ac.uk/handle/1810/244643

Rights: Attribution-NonCommercial-NoDerivs 2.0 UK: England & Wales

Licence URL: http://creativecommons.org/licenses/by-nc-nd/2.0/uk/





Author: Martínez Hurtado, Juan LeonardoAdvisorsLowe, Christopher R.

Source: https://www.repository.cam.ac.uk/handle/1810/244643



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