title: The inherent problem of transflection-mode infrared spectroscopic microscopy and the ramifications for biomedical single point and imaging applications.
abstract: Transflection-mode FTIR spectroscopy has become a popular method of measuring spectra from biomedical and other samples due to the relative low cost of substrates compared to transmission windows, and a higher absorbance due to a double pass through the same sample approximately doubling the effective path length. In this publication we state an optical description of samples on multilayer low-e reflective substrates. Using this model we are able to explain in detail the so-called electric-field standing wave effect and rationalise the non-linear change in absorbance with sample thickness. The ramifications of this non-linear change, for imaging and classification systems, where a model is built from tissue sectioned at a particular thickness and compared with tissue of a different thickness are discussed. We show that spectra can be distorted such that classification fails leading to inaccurate tissue segmentation which may have subsequent implications for disease diagnostics applications.
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Bassan
authors.forename: Joe
authors.initials: J
authors.lastname: Lee
authors.forename: Ashwin
authors.initials: A
authors.lastname: Sachdeva
authors.forename: Juliana
authors.initials: J
authors.lastname: Pissardini
authors.forename: Konrad M
authors.initials: KM
authors.lastname: Dorling
authors.forename: John S
authors.initials: JS
authors.lastname: Fletcher
authors.forename: Alex
authors.initials: A
authors.lastname: Henderson
authors.forename: Peter
authors.initials: P
authors.lastname: Gardner
mesh_terms: D000042:Absorption; D003596:Cytosine / Q000737:chemistry; D006801:Humans; D008297:Male; D008853:Microscopy; D011467:Prostate / Q000166:cytology* / Q000473:pathology*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003596:Cytosine