Universal thermometry of solid–liquid interfacial thermal conductance

Solid–liquid interfacial thermal conductance (ITC) critically influences heat transport in microfluidic, electronic, and energy systems, yet most optical thermometry techniques are limited to specific metal–liquid interfaces. In this work, we introduce a universal broadband square-pulsed thermometry method that enables simultaneous quantification of ITC across a wide range of arbitrary solid–liquid interfaces while also providing accurate measurements of nanoscale liquid-film thickness. To validate the method, we applied it to Al-water interfaces, yielding ITC values in the range of 50–55 MW m−2 K−1, consistent with prior studies. The technique also reveals markedly lower ITCs for glass-water (9.9 MW m−2 K−1) and Si-water (5.7 MW m−2 K−1), and further measurements on Al-silicone oil (∼10 MW m−2 K−1) and poly(methyl methacrylate) (PMMA)-silicone oil (∼0.4 MW m−2 K−1) extend the validation to highly viscous nonpolar liquids and polymer-liquid interfaces. These results highlight the capability of the method to capture thermal transport differences across diverse solid-liquid combinations. Further comparisons with acoustic/diffuse mismatch models and molecular dynamics simulations, together with theoretical analysis, highlight the influence of vibrational mismatch, wettability, and surface condition on interfacial thermal transport. This broadly applicable technique enables rapid, quantitative characterization of solid-liquid interfacial thermal transport, with broad implications for interfacial heat transfer science and technology.