Canine Tongue-Inspired Superspreading-Enhanced Cross Scale-Coupled Evaporation for Thermal Management

Overheating is a major cause of device failure. Thin-film evaporative cooling leverages the latent heat of liquid phase change, but its performance is often governed by the balance between interfacial liquid supply and interfacial mass-transfer kinetics. The canine tongue maintains a continuously wetted surface through rapid saliva replenishment and evaporation during thermoregulation. Here, previously unreported nanocilia on the tongue surface of the Beagle (Canis lupus familiaris) are identified. These nanocilia coat microscale papillae, revealing a naturally evolved micro-nano hierarchical architecture. Inspired by this architecture, a bioinspired cross-scale continuous surface (BioCCS) integrating microgrooves and nanowires is developed. Microgrooves promote stable liquid spreading, while nanoscale confinement modulates interfacial water interactions and weakens interfacial hydrogen bonding, together establishing a cross-scale coupled evaporation mechanism (CCEM) bridging micro-nano-molecular scales. Tested at 80 °C, a temperature relevant to device reliability, BioCCS achieves an evaporation rate of 31.36 kg h-1 m-2, enabling a self-sustained passive cooling system with a 150% enhancement in heat dissipation compared with an unmodified surface. These results provide a concept for autonomously sustained phase change cooling under subboiling conditions.