Laser-induced processing of thermal cloaks enabling heat shielding

Thermal cloaks based on multi-layered structure consisted of laser-induced graphene (LIG) layers, are designed to shield heat from a central region and keep its temperature distribution. Complex thermal cloak structures with tunable thermal conductivities can be precisely processed by programming laser directly scanning method. The effect of laser processing parameters on thermal conductivity of LIG is investigated. To obtain the optimal design of the LIG-based thermal cloak, finite element simulations are performed for monolayer, bilayer and multilayer thermal cloaks. The designed thermal cloaks are assembled by alternating LIG layers and polyimide (PI) layers. With same LIG thermal conductivities, the monolayer, bilayer and multilayer thermal cloaks have good heat shielding performance, and the temperature distribution in the central region is 0.1 K/mm, 0.0793 K/mm, and 0.043 K/mm respectively. More importantly, the LIG-based thermal meta-devices have the advantages of convenience, flexibility and high accuracy, which provide a feasible method for thermal manipulation of electronic packages.