Dynamic infrared-reflective materials based on reflectin films
Reflectin proteins are proteins derived from cephalopods (certain species of squid) which have unusual optical properties. Disclosed herein are thin films of reflectin proteins which can be tuned to reflect infrared light. Advantageously, the films can be tuned dynamically over short time scales, to reflect at different wavelengths. Disclosed herein are novel infrared-reflective coatings, methods of making such coatings, and infrared-reflective objects such as textiles, building materials, and camouflage materials.
1. A method of modulating the infrared reflectance of a reflectin film by application of one or more stimuli,
comprising exposing the reflectin film to an electrical stimulus, a mechanical stimulus, or both;
wherein the reflectin film consists essentially of reflectin protein; and
wherein a change in the infrared reflectance of the film occurs as a result of changes in thin film interference effects in response to the stimulus.
2. The method of claim 1 , wherein
the one or more stimuli comprises a mechanical stimulus.
3. The method of claim 2 , wherein
wherein the reflectin film is adhered to a flexible substrate; and
the mechanical stimulus comprises tension applied to the flexible substrate such that the reflectin film is stretched and deforms to assume a thinner conformation than it had prior to the application of the tension.
4. The method of claim 3 , wherein
wherein the flexible substrate and reflectin film are stretched to 115% or less of their original length.
5. The method of claim 3 , wherein
the thickness of the reflectin film prior to application of the tension is such that its peak reflectance wavelength is above 700 nm and the thickness of the reflectin film during the application of tension decreases such that its peak wavelength reflectance is less than 700 nm.
6. The method of claim 3 , wherein
the flexible substrate is a textile.
7. The method of claim 2 , wherein
the mechanical stimulus is applied by micromechanical actuators.
8. The method of claim 2 , wherein
the one or more stimuli further comprises a chemical stimulus.