Engineers and scientists have been trying to discover the ultimate "cloaking" device -- not just as a hat trick to make things invisible -- but for its applications in defense technology. Now, a team from the NUS Department of Electrical & Computer Engineering led by Dr Qiu Chengwei, has successfully come out with a thermal illusion device to control thermal camouflage and invisibility using thermotic materials. Thermotics is a branch of science dealing with heat and thermodynamics.
Every natural object exhibits thermal signatures. However, if these signals are blocked or masked, then these objects become undetectable. If you can remember the Predator movie (starring Arnold Schwarzenegger) -- the creature is invisible and is also effectively camouflaged to blend in with its surroundings making it difficult for it to be tracked down. But this hi-tech creature has an advantage over its hunters as it detects them using thermal imaging.
A "predator" like the one in the movie Predator, to some extent, is actually realizable, using Dr Qiu's invention. His device could block thermal signatures (leading to invisibility) and provide illusionary camouflage at the same time. He and his team's findings were published recently in Advanced Materials as well as Physical Review Letters. Besides academic journals, the researchers' breakthrough has also been extensively highlighted by online scientific publications in the US and UK.
Said Dr Qiu, "This is the first time that such a cloak has been proven to work effectively, based on thermotics. Our success means that now we have a cloaking technology that is cost-effective and easily scalable and applicable to even bigger objects such as soldiers on night missions. We have managed to control the thermal illusions' shapes, material properties, distributions, and locations using bulk natural materials without sophisticated fabrication. This drastically overcomes practical and challenging limitations of metamaterials which are not found in nature and hence would require complicated and complex design to imbue them with special properties. Our new technology has also overcome limitations like narrow bandwidth and polarisation-dependence."
The team comprising Dr Qiu, Dr Han Tiancheng, Ms Bai Xue, Associate Professor John T L Thong and Professor Li Baowen (NUS Department of Physics), has carefully investigated their device in both time-dependent and temperature-dependent conditions and have found it to demonstrate excellent thermodynamic performance. The technology is ready to roll out for military applications.
Their research has also introduced a new dimension to the emerging field of "phononics" which is the controlling and manipulating of heat flow with phonons (particles which transmit heat within solid materials). A spinoff application of their research, said Dr Qiu, would be in heat management of highly packed electronic circuits, interconnectors and batteries.
- Tiancheng Han, Xue Bai, Dongliang Gao, John Thong, Baowen Li, Cheng-Wei Qiu. Experimental Demonstration of a Bilayer Thermal Cloak. Physical Review Letters, 2014; 112 (5) DOI: 10.1103/PhysRevLett.112.054302
- Tiancheng Han, Xue Bai, John T. L. Thong, Baowen Li, Cheng-Wei Qiu. Full Control and Manipulation of Heat Signatures: Cloaking, Camouflage and Thermal Metamaterials. Advanced Materials, 2014; DOI: 10.1002/adma.201304448
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