A NIR-Spectroscopy-Based Approach for Detection of Fluids in Rectangular Glass Micro-Capillaries

In this work, we present a micro-opto-fluidic platform to distinguish water and alcohol samples flowing in rectangular glass micro-capillaries laid onto a bulk Aluminum mirror illuminated by the broadband radiation emitted by a Tungsten lamp. The fluid detection is based on the spectral analysis of the light reflected by the micro-structure in the near-infrared region from 1.0 μm to 1.7 μm. A theoretical model was implemented to study light propagation in the channel, taking into account absorption effects, and the results of the simulation are in good agreement with the experimental spectra obtained by testing water, ethanol, isopropanol and ethylene glycol.