Pangolin‐Inspired Stretchable, Microwave‐Invisible Metascale

Abstract

Microwave‐invisible devices are emerging as a valuable technology in various applications, including soft robotics, shape‐morphing structures, and textural camouflages, especially in electronic countermeasures. Unfortunately, conventional microwave‐absorbing metastructures and bulk absorbers are stretching confined, limiting their application in deformable or special‐shaped targets. To overcome such limitations, a conceptually novel soft–rigid‐connection strategy, inspired by the pangolin, is proposed. Pangolin‐inspired metascale (PIMS), which is a kind of stretchable metamaterial consisting of an electromagnetic dissipative scale (EMD‐scale) and elastomer, is rationally designed. Such a device exhibits robust microwave‐absorbing capacity under the interference of 50% stretching. Besides, profiting from the covering effect and size‐confined effect of EMD‐scale, the out‐of‐plane indentation failure force of PIMS is at least 5 times larger than conventional device. As a proof of concept, the proposed device is conformally pasted on nondevelopable surfaces. For a spherical dome surface, the maximum radar cross‐section (RCS) reduction of PIMS is 6.3 dB larger than that of a conventional device, while for a saddle surface, the bandwidth of 10 dB RCS reduction exhibits an increase of 83%. In short, this work provides a conceptually novel platform to develop stretchable, nondevelopable surface conformable functional devices.

Enhancing the Low/Middle‐Frequency Electromagnetic Wave Absorption of Metal Sulfides through F− Regulation Engineering

“…Aside from controlling morphology [ 16–18 ] and electron interactions, [ 19,20 ] the careful design and control of other parameters, such as defect levels, [ 21–23 ] electronic conductivity, [ 24 ] composition features, [ 25–27 ] and interfacial construction, [ 28,29 ] become key factors in engineering EMW absorption properties. To regulate defect levels and electronic conductivity, it has been reported that anion doping (such as N, [ 30 ] S, [ 31 ] and P [ 32 ] ) can improve defect levels by degrading crystal lattice and vacancy formation.…”

A Flexible, Mechanically Strong, and Anti‐Corrosion Electromagnetic Wave Absorption Composite Film with Periodic Electroconductive Patterns

“…[ 32 ] Previous reports have shown that power loss (PL) was positively correlated with the electrical field tangent to the SLUs, while the normal component of the electric field did not contribute to the power loss. [ 36 ] Compared to the solid counterpart, the electric field intensity of the SLUs structure increased by three times and exhibited a specific spatial distribution (Figure 3c). With quantitative analysis, the PL was expressed by: where σ and E || denote the conductivity of the SLUs and intensity of the tangential electric field, respectively.…”

“…[34,35] Currently, this type of patterning in substrates is largely managed by multistep photolithographic processes at the expense of finely controlling features, which is necessary for tuning a combination of properties. [36,37] Additionally, these complex strategies and costly equipment make such routes less appealing for massproduction compared to the hard-template method.…”

Hydro/Organo/Ionogels: “Controllable” Electromagnetic Wave Absorbers

“…[ 2,3 ] Nowadays, the rapid development of soft robotics, deformable structures, and camouflages boosts the demands for flexible and microwave‐invisible materials in the application of electronic countermeasures and precision equipment protection. [ 4,5 ] Conventional microwave‐absorption materials (MAMs), such as carbon‐based materials (graphene, MXene, carbon nanotubes), [ 6,7 ] metal‐based materials (transition metal oxides/sulfides, alloy), [ 8 ] and conductive polymer [ 9 ] provided super absorption efficiency but very limited controllability and poor processability. Recently, some flexible MAMs have been developed for more complicated target applications, such as metastructures and polymer‐reinforced composites.…”