Fig. 2: Thermal and mechanical characterization.

a Typical frequency-domain thermal reflectance (FDTR) data plot and the best least-square fitting to the heat transfer model. Inset: picture of tested sample and 9 test spots marked in blue, scale bar, 5 mm. b Histograms summarizing thermal conductivity of the copper nanowire (CuNW) array layer extracted from the FDTR measurements at different test spots, error bar data listed in Supplementary Information Table S1. c Schematic showing the principle of ASTM D5470 standard thermal measurements. d Pressure-dependent thermal resistance of liquid-infused nanostructured composites (LINCs) without and with different thermal-bridge liquids, tested under the ASTM D5470 standard, in which the Liquid-Metal-LINC shows an extremely low thermal resistance (<1 mm² K W⁻¹) above 50 Psi. Two commercially available thermal pastes with reported thermal conductivities of 8.5 W m K⁻¹ and 14.2 W m K⁻¹ are measured in the same setup as references, error bar data accessible in Source Data. e Stiffness characterization of an isolated CuNW bundle using in situ cylindrical flat punch indentation. Inset: Scanning electron microscopic image of the nanoindentation process on an isolated nanowire bundle, scale bar, 5 μm. f Displacement vs Stiffness curve in the continuous stiffness measurement showing the stiffness results for single-sided and double-sided films each from three different indentation locations, where the double-side film shows about half the stiffness measured from the single-sided film, indicating the structural benefit of the double-sided design. Source data are provided as a Source Data file.