Multi-reflection polarimetry in microfluidics

Al-Hafidh, M. H., Glidle, A., Wilson, R. , Kelly, A. E. , Reboud, J. and Cooper, J. M. (2019) Multi-reflection polarimetry in microfluidics. IEEE Sensors Letters, 3(10), 3502104. (doi:10.1109/LSENS.2019.2943688)

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Abstract

The field of microfluidics promises new portable, low-cost sensing systems, as well as the capabilities to measure the physical or chemical properties of precious samples, for which only small volumes are available. However, when using microfluidic channels with millimeter to micron scale dimensions, together with optical sensing methods, these configurations result in short path lengths over which the signal can be acquired. Whilst polarimetry would greatly benefit from using small volumes, providing important information on the structure of chiral biomarkers in life sciences, the small interrogation volumes associated with the use of minute samples decreases the numbers of molecules in the light path that cause an optical rotation and reduces the sensitivity of the technique. Here, we show that when an optical beam, passing through a chiral sample, undergoes multiple reflections from suitably aligned external micromirrors, the usual cancelling out of the optical rotation, that occurs when the rotated polarized beam is passed back through a solution following reflection at a single mirror, can be negated. This enables the chirality of molecular species present in a microfluidic sample to be measured with increased sensitivity. This approach was validated experimentally using solutions of D-(+)-glucose as a model system, by investigating the effect of multiple reflections of a linearly polarized He-Ne laser beam and a 403 nm diode laser beam across the microfluidic channel. It was found that there was a 30-fold enhancement in the limit of detection with as few as 11 reflections through the sample.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wilson, Dr Robert and Kelly, Professor Anthony and Cooper, Professor Jonathan and Reboud, Dr Julien and Glidle, Dr Andrew and Al-Hafidh, Ms Maab
Authors: Al-Hafidh, M. H., Glidle, A., Wilson, R., Kelly, A. E., Reboud, J., and Cooper, J. M.
College/School:College of Science and Engineering > School of Engineering > Biomedical Engineering
College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:IEEE Sensors Letters
Publisher:IEEE
ISSN:2475-1472
ISSN (Online):2475-1472
Published Online:25 September 2019
Copyright Holders:Copyright © 2019 IEEE
First Published:First published in IEEE Sensors Letters 3(10):3502104
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
617021Advanced Diagnostics using PhononicsJonathan CooperEngineering and Physical Sciences Research Council (EPSRC)EP/K027611/1ENG - BIOMEDICAL ENGINEERING
625501Bio-PHONONICS: Advanced Microfluidics & Diagnostics using Acoustic Holograms Bio-PhononicsJonathan CooperEuropean Research Council (ERC)340117ENG - BIOMEDICAL ENGINEERING