Thermal Cloaking and Heat Signature Control with Nanostructured Films

Introduction
What is Thermal Cloaking?
How Does Thermal Cloaking Work?
What are These ‘Cloaks’ Made of?
Applications of Thermal Cloaking
A Practical Asset
References

Achieving invisibility in the world of precision sensing is hardly a trivial task, especially when it comes to concealing heat, a highly prevalent and recognisable signature of strategic infrastructure. 

To remain undetected by thermal imaging systems, modern military is exploring the advantages of nanostructured camouflage.¹

Image Credit: WHITE RABBIT83/Shutterstock.com

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What is Thermal Cloaking?

Invisibility and cloaking devices gained significant interest amongst scientific communities two decades ago, when researchers from Duke University and Imperial College London theorized that light can be bent around an object to make it appear ‘invisible’. The method revolved around metamaterials, conceptual materials composed of dielectrics and semiconductors with electromagnetic properties that allow them to manipulate light paths.^2,3

The idea quickly gained momentum and attracted the attention of defence institutions. Transformation Optics became a promising candidate for next-generation stealth coatings, with the potential to conceal operators, vehicles, and strategic infrastructure.^2-4

However, thermal cloaking must contend with diffusive, irreversible heat transport rather than just wave propagation, which makes it difficult to suppress the thermal contrast between the object and its surroundings over time.⁵ As a result, electromagnetic cloaking alone is insufficient for hiding thermal signatures.^5,6

Troops, vehicles, and logistical assets remain vulnerable to the threat from night-vision devices, heat-seeking missiles, and any other form of infrared detection.⁶

Thermal cloaking (TC) means to prevent that. If emitted infrared waves cannot be reliably redirected, an alternative is to redistribute the thermal energy of the object before it gets emitted. This is the underlying principle of TC.⁷

How Does Thermal Cloaking Work?

Heat transport is a process of energy transfer between atoms aimed at bringing an object to thermodynamic equilibrium with its surroundings.⁸ This process can be described by phonons, mechanical waves caused by vibrational atomic motion.⁸ In other words, heat is transferred through a body to its surface by atoms pushing each other in wave-like motion.

What happens next depends on the interface between the body and the surrounding media. In a general case, phonons propagate efficiently through the body towards the surface, where the vibration causes charge motion and dipole fluctuations, and the energy is released as an infrared electromagnetic wave⁹.

But if the interface has an extra layer of material with a different atomic structure, it disrupts phonon transport, causing atomic vibrational waves to scatter and deflect. This delays the heat transfer.¹⁰ So, smaller portions of energy leave as IR waves per unit time, decreasing the contrast between the body and its surroundings on a thermal imaging device.

This is precisely what nanostructured film 'cloaks' do. By artificially modifying the nanostructure at the interface between the object and its environment, they create an impedance mismatch that scatters energy, delaying and spatially redistributing thermal radiation.¹¹

Combined with optical wavelength-selective coating designs, the fraction of the remaining emitted IR waves can be redirected to minimize thermal visibility of the object, creating the stealth effect.^2.3

What are These ‘Cloaks’ Made of?

Image Credit: Vision By Luca Spoo/Shutterstock.com

Nanostructured coatings are manufactured from materials with tailorable thermal-infrared response. This includes dielectric oxides, semiconductors, polymer-based nanocomposites, and plasmonic materials.¹¹

What makes them both unique and similar is that their modified architecture allows for the tailoring of permeability, permittivity, and thermal emissivity, the three parameters responsible for thermal and electromagnetic signature control. When designed carefully, layers of these materials create coatings with the parameters closely matched for efficient heat signature cloaking.¹¹

Applications of Thermal Cloaking

There are numerous official documents showcasing examples of nanostructure-modified coatings being used for military and defence applications. While details are undisclosed, the documents demonstrate the direct relevance of the technology for applied heat signature suppression.^1,12-14

In 2020, the US Defence Systems Information Analysis Centre (DSIAC) produced an extensive report covering soldier/vehicle signature management. The report covers multiple metamaterials developed for enhanced thermal camouflaging to shortlist candidate materials for military applications. ¹

A mention-worthy example is carbon nanotube-doped aerogel developed by researchers at Donghua University¹⁵. The material demonstrated low surface emissivity and thermal conductivity, making the human heat signature practically invisible.

A more applied and recent example is outlined in a 2024 patent filed by Advanced Material Development (UK)¹². The team developed a carbon-nanotube and graphene-based coating intended for thermal camouflage surfaces. Infrared camera tests showed a clear reduction in apparent temperature when the coating was applied and electrically tuned.

Another high-priority target for nanostructured films is heat control for temperature-sensitive electronics. This expands defence-relevant applications beyond thermal camouflage. Recent advances in nanomanufacturing discussed in a 2025 Advanced Materials review, enable micro- and nanostructured coatings that regulate heat flow via the same principle of phonon transport.¹³

This research direction was identified as one of the main strategic focuses for next-generation electronics and digital systems by the Strategic Research and Innovation Agenda (SRIA) 2024-2030, Innovative Advanced Materials for Europe (IAM4EU).¹⁴

Learn more about stealth technology, here.

A Practical Asset

Having emerged as a theoretically ambitious concept, thermal cloaking has become a practical asset in the defence sector.

As the boundaries of nanoscale engineering and manufacturing expand, both sensing and cloaking capabilities continue to improve. In this context, advances in thermal signature control are expected to play an increasingly important role in military infrastructure, while also finding relevance in other heat-sensitive technologies such as nanoelectronics and solid-state information systems.

References

1. Prussing KF. Recent Developments in Soldier and Vehicle Signature Management Technologies. Defense Systems Information Analysis Center (DSIAC); 2020.
2. Pendry JB, Schurig D, Smith DR. Controlling electromagnetic fields. Science. 2006;312(5781):1780-1782. DOI:10.1126/science.1125907, https://www.science.org/doi/10.1126/science.1125907
3. Leonhardt U. Optical Conformal Mapping. Science. 2006;312(5781):1777-1780. DOI:10.1126/science.1126493, https://www.science.org/doi/10.1126/science.1126493
4. Derov JS, Hammond R, Youngs IJ. The history of the early years of metamaterials in USA and UK defense agencies. J Opt. 2017;19(8):084002. DOI:10.1088/2040-8986/aa73bf, https://iopscience.iop.org/article/10.1088/2040-8986/aa73bf
5. Yang FB, Huang JP. Unveiling the Thermal Cloak: A Journey from Theoretical Foundations to Cutting-Edge Applications. In: Diffusionics. Springer Nature Singapore; 2024:91-106. DOI:10.1007/978-981-97-0487-3_5, https://link.springer.com/chapter/10.1007/978-981-97-0487-3_5
6. Havens KJ, Sharp EJ. Remote Sensing. In: Thermal Imaging Techniques to Survey and Monitor Animals in the Wild. Elsevier; 2016:35-62. DOI:10.1016/B978-0-12-803384-5.00003-8, https://www.sciencedirect.com/science/article/pii/B9780128033845000038
7. Han T, Bai X, Gao D, Thong JTL, Li B, Qiu CW. Experimental Demonstration of a Bilayer Thermal Cloak. Phys Rev Lett. 2014;112(5):054302. DOI:10.1103/PhysRevLett.112.054302, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.054302
8. Ziman JM. Electrons and Phonons: The Theory of Transport Phenomena in Solids. Reprinted. Clarendon Press; 2007.
9. Modest MF. Radiative Heat Transfer. 3rd edition. Academic Press; 2013.
10. Bar-Cohen A, Matin K, Narumanchi S. Nanothermal Interface Materials: Technology Review and Recent Results. J Electron Packag. 2015;137(4):040803. DOI:10.1115/1.4031602, https://asmedigitalcollection.asme.org/electronicpackaging/article/137/4/040803/371023
11. Chen G. Nanoscale Energy Transport And Conversion: A Parallel Treatment Of Electrons, Molecules, Phonons, And Photons. Oxford University Press, New York, NY; 2005. DOI:10.1093/oso/9780195159424.001.0001, https://academic.oup.com/book/9780195159424
12. JOHNSTONE J, DALTON A, LYNCH P, LARGE M, OGILVIE S. DEVICES WITH LOW THERMAL EMISSIVITY. 2024;(EP 21171668):EP 4 301 697 B1.
13. Zhang Y, Li H, Zhou Y, et al. Beyond Conventional Cooling: Advanced Micro/Nanostructures for Managing Extreme Heat Flux. Adv Mater. 2026;38(5):e04706. DOI:10.1002/adma.202504706, https://onlinelibrary.wiley.com/doi/10.1002/adma.202504706
14. Strategic Research and Innovation Agenda (SRIA). Innovative Advanced Materials for Europe (IAM4EU); 2024. https://www.iam-i.eu/wp-content/uploads/2025/02/SRIA-Innovative-Advanced-Materials-for-Europe.pdf
15. Xu R, Wang W, Yu D. A novel multilayer sandwich fabric-based composite material for infrared stealth and super thermal insulation protection. Compos Struct. 2019;212:58-65. DOI:10.1016/j.compstruct.2019.01.032, https://www.sciencedirect.com/science/article/pii/S0263822318331674

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