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Joly M, Deng T, Morhart TA, Wells G, Achenbach S, Bégin-Drolet A, Greener J. Scanning Aperture Approach for Spatially Selective ATR-FTIR Spectroscopy: Application to Microfluidics. Anal Chem 2021; 93:14076-14087. [PMID: 34636233 DOI: 10.1021/acs.analchem.1c01614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We present a novel spectroscopy accessory that can easily convert any Fourier transform infrared (FTIR) spectrometer into a fully automated mapping and assaying system. The accessory uses a multiridge attenuated total reflection (ATR) wafer as the sensing element coupled with a moving aperture that is used to select the regions of interest on the wafer. In this demonstration, the accessory is combined with a series of parallel micropatterned channels, which are positioned co-linear with the light-coupling ridges on the opposite side of the ATR wafer. The ATR spectroscopy microfluidic assay accessory (ASMAA) was used in continuous mapping mode to scan perpendicular to the ATR ridges, revealing complex but repeatable oscillations in the spectral intensities. To understand this behavior, the light path through the optical components was simulated with consideration of the aperture position, ridge-to-channel alignment, and excitation beam profile. With this approach, the simulation reproduced the experimental mapping results and provided evidence that the measurement position and area changed with the aperture position. To demonstrate the assay mode, we obtained spectra along the centerline of individual microchannels and determined noise baselines and limits of detection.
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Affiliation(s)
- Maxime Joly
- Département de génie mécanique, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Tianyang Deng
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Tyler A Morhart
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.,Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - Garth Wells
- Canadian Light Source, Saskatoon, SK S7N 2V3, Canada
| | - Sven Achenbach
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada
| | - André Bégin-Drolet
- Département de génie mécanique, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Jesse Greener
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada.,CHU de Québec, centre de recherche, Université Laval, 10 rue de l'Espinay, Québec, QC G1L 3L5, Canada
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