On using the anisotropy in the thermal resistance of solid–fluid interfaces to more effectively cool nano-electronics

As power-intensive electronic components are further miniaturised into nanodevices, their heat dissipation is a serious operational and safety concern. While nanochannels and nanofins are often used for facilitating heat dissipation, the liquid-solid interfaces that form (Kapitza resistance), become significant barriers to heat transfer. We demonstrate that the thermal resistance of these interfaces is strongly anisotropic. The resistance of an interface to heat transfer parallel to the interface (solid surface) is significantly smaller than the more well-known Kapitza resistance (associated with heat transfer across the interface – perpendicular to the solid surface) and is even lower than that of the bulk fluid. As a result, if devices are designed to dissipate heat parallel to an interface, heat dissipation can be significantly enhanced. Our studies are also able to explain the molecular basis of this observed anisotropy in interfacial resistance, which has hitherto remained unreported for solid–liquid interfaces.