Nanotechnology unlocks squid skin secrets

Taking inspiration from one of nature's most adaptive creatures, researchers from ACS Nano have explored the transformative qualities of squid skin to create a soft film that can regulate its transparency across a large range of wavelengths – visible, infrared, and microwave – all at the same time.

The skin of squid and other cephalopods have unique cells that can reversibly change their shape and appearance to mimic their surroundings, giving them an almost imperceptible exterior.

As one of the many head-scratching abilities found in nature, scientists have long attempted to recreate this highly specialized evolutionary trait.

Having already developed artificial materials that can transition from reflecting to transmitting visible and infrared wavelengths by shifting between different states, scientists had yet to truly narrow down the finesse of such a technique when it comes to microwaves.

However, researchers have recently found that dense networks of electrically conductive materials, such as silver nanowires, could block microwaves. So, a team at the American Chemical Society wanted to integrate these old methods with the new conductive network in a soft film that could quickly transition between shielding visible-to-microwave bands and allowing them through.

Man-made squid skin

To combine the thermal and light-reflecting capabilities with the microwave-resistant surface, the researchers first created a two-layer film by spraying a thin coating of silver nanowires onto a stretched elastomer or "stretchy polymer."

Stretching and contracting the material produced cracks and bumpy wrinkles in the metal surface, which gave the material its thermal and light-reflective function.

By contracting the material to a specific stress level, this silver nanowire-coated elastomer was capable of blocking light, trapping infrared heat, and, finally, shielding up to 99.9% of microwaves that could interfere with potential devices it may be protecting.

Playing around with their new man-made squid skin, the team was able to demonstrate how the material could be used for various applications, such as transmission or blocking of wireless electrocardiography (heartrate) signals; as a blanket to trap body heat or allowing it to escape; or for tracking movements because the material produces temperature changes that are detectable by infrared cameras.

While it's no Predator-level cloaking device, the researchers say that their system's ability to modify its transparency repeatedly and rapidly could benefit dynamic camouflage technologies, energy-efficient buildings, and adaptive personal and healthcare devices.