Shimmering silk has been worn for centuries to be fashionable and to show wealth and status. However in the next few years people may be wearing silk in order to be invisible to the eye. Scientists have made an invisibility cloak out of silk coated in gold.
Invisibility cloaks and other garments are known as metamaterials. This new metamaterial only works on a region of the electromagnetic spectrum between radio and infrared light; known as terahertz waves. Boston area scientists believe that silk can work as an invisibility cloak at wavelengths that are in the visible range. The research into these materials could lead to a wide range of biomedicines and defense options.
Silk’s ability to interface with the human body is a facet of the material that no other metamaterial is capable of at this time.
Invisibility cloaks and their relatives perfect absorbers and perfect reflectors all come under the umbrella of metamaterials , what makes these materials different from other materials is that they don’t derive optical properties from their chemical makeup. Metamaterials obtain their properties from their physical structure.
To create the silk based metamaterial scientists from Tufts and Boston University started with a small (one centimeter) square of silkworm silk and stenciled 10,000 gold resonators. Normally silk allows terahertz waves to pass through it, when the new material was tested with T-rays a resonance was detected. The potential for biomedical uses for this meta material is due to the fact that the human body won’t reject silk based implants and when tested the patterned silk implanted into a muscle still resonated. This product could possibly change the way glucose is detected in the body, eliminating needle pricks. Silk based invisibility also would allow physicians to cloak an organ and see through it to better see tissue and organs that are normally hidden behind others.