Enhancing near-field radiative heat transfer with bio-inspired hierarchical localized resonances

Radiative heat transfer is a pervasive phenomenon in nature, and its effective manipulation is crucial for addressing pressing challenges such as global climate change, the energy crisis, and overheating of electronic devices. However, significant challenges persist in the quest to develop a universal design paradigm that can facilitate transformative breakthroughs in the radiative heat transfer performance. Here, drawing inspiration from hierarchical microstructures in nature, we propose a radiative strategy based on a Morpho-butterfly-like metasurface. In the deep near-field region, this bio-inspired metasurface exhibits a significant advantage in radiative heat transfer capabilities when compared with both films and conventional hyperbolic gratings. This enhancement originates from the intrinsic 3D hierarchical localized resonances within the structure, which effectively modifies the thermophoton tunneling wavevector distribution. This provides an unconventional hyperbolic thermophoton tunneling mode, which in turn effectively enhances the energy spectrum of the thermal metasurface. This investigation establishes a novel platform for efficient manipulating radiative heat transfer through the introduction of bio-inspired structures, with potential applications in a variety of fields, including thermal measurements, thermal management, and next-generation energy devices.