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Proceedings Paper

Mid-IR spectroscopic instrumentation for point-of-care diagnosis using a hollow silica waveguide gas cell
Author(s): Daniel Francis; Jane Hodgkinson; Christopher Walton; Jeremy Sizer; Paul Black; Beth Livingstone; Dawn P. Fowler; Mitesh K. Patel; Ralph P. Tatam
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Paper Abstract

Laser spectroscopy provides the basis of instrumentation developed for the diagnosis of infectious disease, via quantification of organic biomarkers that are produced by associated bacteria. The technology is centred on a multichannel pulsed quantum cascade laser system that allows multiple lasers with different wavelengths to be used simultaneously, each selected to monitor a different diagnostic biomarker. The instrument also utilizes a hollow silica waveguide (HSW) gas cell which has a very high ratio of interaction pathlength to internal volume. This allows sensitive detection of low volume gas species from small volume biological samples. The spectroscopic performance of a range of HSW gas cells with different lengths and bore diameters has been assessed using methane as a test gas and a best-case limit of detection of 0.26 ppm was determined. The response time of this cell was measured as a 1,000 sccm flow of methane passed through it and was found to be 0.75 s. These results are compared with those obtained using a multi-pass Herriot cell. A prototype instrument has been built and approved for clinical trials for detection of lung infection in acute-care patients via analysis of ventilator breath. Demonstration of the instrument for headspace gas analysis is made by monitoring the methane emission from bovine faeces. The manufacture of a hospital-ready device for monitoring biomarkers of infection in the exhaled breath of intensive care ventilator patients is also presented.

Paper Details

Date Published: 17 February 2017
PDF: 10 pages
Proc. SPIE 10072, Optical Diagnostics and Sensing XVII: Toward Point-of-Care Diagnostics, 1007209 (17 February 2017); doi: 10.1117/12.2253074
Show Author Affiliations
Daniel Francis, Cranfield Univ. (United Kingdom)
Jane Hodgkinson, Cranfield Univ. (United Kingdom)
Christopher Walton, Cranfield Univ. (United Kingdom)
Jeremy Sizer, Bedford Hospital NHS Trust (United Kingdom)
Paul Black, Cascade Technologies Ltd. (United Kingdom)
Beth Livingstone, Cascade Technologies Ltd. (United Kingdom)
Dawn P. Fowler, Cranfield Univ. (United Kingdom)
Mitesh K. Patel, Cranfield Univ. (United Kingdom)
Ralph P. Tatam, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 10072:
Optical Diagnostics and Sensing XVII: Toward Point-of-Care Diagnostics
Gerard L. Coté, Editor(s)

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