Thermally Controlled, Active Imperceptible Artificial Skin in Visible‐to‐Infrared Range

Abstract

Cephalopods’ extraordinary ability to hide into any background has inspired researchers to reproduce the intriguing ability to readily camouflage in the infrared (IR) and visible spectrum but this still remains as a conundrum. In this study, a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with a flexible bi‐functional device (active cooling and heating) is developed. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum (thus visible‐to‐IR) and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt to the background of the sophisticated pattern with higher resolution and eventually heightening the level of imperceptibility. As this proof‐of‐concept can be directly worn and conceals the human skin in multispectral ranges, the work is expected to contribute to the development of next‐generation soft covert military wearables and perhaps a multispectral cloak that belongs to cephalopods or futuristic camouflage gadgets in the movies.

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

“…[76,84] For example, a pixelated thermosensitive CLC device can be locally heated to any color by an electric field regardless of the ambient temperature. [87] A photothermal response can also be obtained upon incorporating a photo-absorbing dye in the TR-RC CLC system. [88,89] By illuminating the sample with an appropriate light source, the dye absorbs the incoming light which is converted into heat: an IR dye could be added to a CLC mixture and cause significant heat generation upon illuminating the sample with IR light, for instance.…”

Beyond the Visible: Bioinspired Infrared Adaptive Materials

“…[52] Interestingly, Ko et al designed and developed a soft and skin-like imperceptible device exhibiting the instantaneous thermal cloaking ability in the visible and IR regions. [53] In the experiment, the thermoelectric materials were used to facilitate superior temperature tunability of asprepared device, which helps to achieve the thermal cloaking in the IR range through matching the ambient temperature. Importantly, thermochromic liquid crystals were incorporated into the surface of the device, which enabled the thermal cloaking in the visible region.…”

Research Progress of Bionic Adaptive Camouflage Materials

“…Thus, in recent years, there has been an emerging demand on how to make camouflaged targets better adapt to the complex battlefield background. Meanwhile, bionic camouflage technology is becoming one of the vital ways to solve the focus issue (Lee et al, 2020;Xu et al, 2020). Organisms from many different phyla have evolved an impressive arsenal of light manipulation strategies that rely on the ability to generate and dynamically reconfigure hierarchically structured, complex optical material designs, often involving soft or fluid components.…”

“…In nature, millions of living beings have undergone hundreds of millions of years of evolution, with reasonable and optimized structural features and adaptability to specific environments. (Lee et al, 2020).…”

“…FIGURE 1 | Dynamic camouflage ability of cephalopods both in the visible and infrared spectrum(Lee et al, 2020).…”