Characterization of thin film evaporation in micropillar wicks using micro-Raman spectroscopy

Thin film evaporation on microstructured surfaces is a promising strategy for high heat flux thermal management. To enhance fundamental understanding and optimize the overall heat transfer performance across a few microns thick liquid film, however, requires detailed thermal characterizations. Existing characterization techniques using infrared thermometry or contact-mode temperature sensors such as thermocouples and resistance temperature detectors cannot accurately measure the temperature of the thin liquid film near the three-phase contact line due to the restriction of low spatial resolution or temperature sensitivity. In this work, we developed a non-contact, in situ temperature measurement approach using a custom micro-Raman spectroscopy platform which has a spatial resolution of 1.5 μm and temperature sensitivity within 0.5 °C. We utilized this method to characterize thin film evaporation from fabricated silicon micropillar arrays. We showed that we can accurately measure the local thin film temper...