title: Structural Characterization of a Capillary Microfluidic Chip Using Microreflectance.
abstract: The structural characterization of capillary microfluidic chips is important for reliable applications. In particular, nondestructive diagnostic tools to assess geometrical dimensions and their correlations with control processes are of much importance, preferably if they are implemented in situ. Several techniques to accomplish this task have been reported; namely, optical coherence tomography (OCT) jointly with confocal fluorescence microscopy (CFM) to investigate internal features of lab-on-a-chip technologies. In this paper, we report on the use of a simple optical technique, based on near-normal incidence microreflectance, which allows mapping internal features of a microfluidic chip in a straightforward way. Our setup is based on a charge-coupled device camera that allows a lateral resolution of ∼2.5 µm and allows us to measure in the wavelength range of 640-750 nm. The technique takes advantage of the Fabry-Perot interferences features in the reflectance spectra, which are further analyzed by a discrete Fourier transform. In this way, the amplitude of the Fourier coefficients is modulated by the presence of a microfluidic channel.
authors.affiliation: 1 Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Lastras-Martínez
authors.affiliation: 1 Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Raul E
authors.initials: RE
authors.lastname: Balderas-Navarro
authors.affiliation: 2 CONACyT-Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Castro-García
authors.affiliation: 1 Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Karen
authors.initials: K
authors.lastname: Hernández-Vidales
authors.affiliation: 1 Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Juan
authors.initials: J
authors.lastname: Almendarez-Rodríguez
authors.affiliation: 1 Universidad Autónoma de San Luis Potosí, Instituto de Investigación en Comunicación Óptica, San Luis Potosí SLP, México.
authors.forename: Rafael
authors.initials: R
authors.lastname: Herrera-Jasso
authors.affiliation: 3 STRATEC Consumables GmbH, Anif, Austria.
authors.forename: Adrian
authors.initials: A
authors.lastname: Prinz
authors.affiliation: 3 STRATEC Consumables GmbH, Anif, Austria.
authors.forename: Iris
authors.initials: I
authors.lastname: Bergmair
keywords: Capillary microfluidic chip; dimensional metrology; microreflectance; microscopy; tomography