Design of active thermal cloak. (a) Multiple TE components are arranged around the air
hole with equal distance on the Carbon Steel plate. Blue TE components absorb incident
thermal flux while red ones release heat back to the plate. In the demonstration, heat flows
from bottom to top. As a result, grey TE components can stay inactive as they do not
absorb or release heat, but they can be activated if heat flows in other directions. (b)...
(September 21, 2015) Thermal cloaking, as an ultimate thermal “illusion” phenomenon, is the result of advanced heat manipulation with thermal metamaterials—heat can be guided around a hidden object smoothly without disturbing the ambient thermal environment. However, all previous thermal metamaterial cloaks were passive devices, lacking the functionality of switching on/off and the flexibility of changing geometries. In this letter, we report an active thermal cloaking device that is controllable. Different from previous thermal cloaking approaches, this thermal cloak adopts active thermoelectric components to “pump” heat from one side to the other side of the hidden object, in a process controlled by input electric voltages. Our work not only incorporates active components in thermal cloaking but also provides controllable functionality in thermal metamaterials that can be used to construct more flexible thermal devices.