2023-06-30 16:45:20
A new soft material, inspired by squid skin, has made possible a switchable shield for light, heat and microwaves.
The achievement is the work of the team of Leilei Liang, from Nanjing University in China.
The new material is applied in the form of a soft film and is capable of regulating its transparency in a wide range of wavelengths (visible, infrared and microwave) simultaneously.
In tests, the researchers used the material in smart windows and in sanitary monitoring and temperature management applications.
Iridocytes and chromatophores, found only on the skin of squid and other cephalopods, reversibly change orientation and alter the animals’ appearance. In the same way, there are artificial materials that go from reflecting to transmitting visible and infrared wavelengths, changing the texture of their surface. Since the microwaves are much larger than the structures that give the desired texture to such surfaces, there is no interaction.
However, it was recently discovered that certain dense networks of electrically conductive materials, such as silver nanowires, can block microwaves. So Liang and his colleagues set out to embed surface structures with a conductive network into a soft film that could quickly switch from blocking visible bands to blocking microwaves, or letting them through.
The researchers created a two-tiered film by applying a thin layer of silver nanowires onto a stretched elastomer. The stretching and contraction of the material produced irregular cracks and wrinkles, respectively, in the metal surface. The researchers then shrunk the material to a tension of -30%, and it blocked light, trapped heat (infrared radiation), and kept out up to 99.9% of microwaves that could interfere with the devices to be protected. .
Compression of this soft material blocks a wide range of wavelengths, including visible light (left), and stretching lets them through (right). (Image: adapted from ACS Nano 2023, DOI: 10.1021/acsnano.3c01836)
In addition, the team demonstrated how the material could be used in various applications:
-To transmit or block wireless electrocardiography signals.
-As a blanket to trap body heat or allow it to escape.
-To track movement, since the materials produce temperature changes detectable by infrared cameras.
The researchers say the system’s ability to repeatedly and rapidly change its transparency could benefit dynamic camouflage technologies, energy-efficient buildings, and personal and healthcare adaptive devices.
Leilei Liang and her colleagues discuss the technical details of their new material and the tests carried out with it in the academic journal ACS Nano, under the title “An Adaptive Multispectral Mechano-Optical System for Multipurpose Applications”. (Source: American Chemical Society)
#Switchable #shield #light #heat #microwaves