Squid are remarkable creatures with many tricks up their many-tentacled sleeves—and chemistry is catching on. New research reports on a squid-inspired soft film that can regulate its transparency across a range of visible, microwave, and infrared wavelengths.
Squid are cephalopods, a class of highly intelligent marine creatures with a unique ability to camouflage themselves and seamlessly blend in with their surroundings. Their invisibility trick is achieved using chromatophores, which are pigment sacs in the skin that change in visibility as muscles contract around them—in tandem with specialized iridocyte cells that act as iridescent reflectors. Crucially, skin morphology also plays a role, with wrinkled surfaces known to play an important role in light scattering. These natural systems are inspiring the next generation of adaptive light and color manipulation techniques.
Previous research has looked at mimicking cephalopod skin in adaptive optical systems, but due to material dispersion and some micro- or nanostructure characteristics, many dynamic electromagnetic responses occur only at specific optical frequencies. Now, researchers working in China and Singapore have taken this further to design an adaptive multispectral mechano-optical system with an effective range from visible light to microwaves. The system, described in their recent ACS Nano article, is based on bilayer films consisting of rigid silver nanowire (AgNW) and soft acrylic dielectric elastomer (ADE) and can reconfigure its surface morphology through mechanical contraction and stretching.
The authors report that, unlike traditional systems that function through only one morphological feature, their system integrates two surface morphologies—wrinkles and cracks—and is therefore able to achieve transition between the two.
When the material contracts, the wrinkles work like iridocytes, forming a bumpy surface that enhances visible–infrared light scattering and strengthens microwave shielding. And in the stretched state, the cracks, behaving like chromatophores, serve as gates to allow visible–infrared light transmission and disrupt conductive networks for microwave transmission.
This material, with on-demand tunability and wide spectral range, could find utility in applications such as infrared camouflage technology, smart windows, health monitoring, and temperature management.