What can we learn from krill?

Upon facing the challenge of climate change , more and more researchers are looking to learn from biological organisms. This overall area of research is called biomimetic design. Biomimetic design aims to study biological organisms and their mechanisms and apply this knowledge to our artificial design to make it more efficient and better.

The research team at the University of Toronto was inspired by marine life to design a low-cost, innovative “optofluidic” system that helps buildings save energy for lighting, heating, and cooling by dynamically changing the appearance of their exteriors.

So what did krill do to catch the attention of the researchers? Krill, which are small shrimp-like organisms that are whales’ favorite food, are transparent in their appearance. This can be problematic when ultraviolet light is strong because it can damage their internal organs. So, krill has developed a shading system that uses colorful pigment granules beneath their skin to darken themselves when it’s too bright out. As you can see in the left column of the diagram below, the pigments on krill create a bloom-like pattern when in use, and this spread of color gives the overall appearance more orange tint than before, thus protecting them from the sun’s UV rays.

Credit : Nature’s Communication

Diagram a to d focus on the biological mechanism of krill’s pigment cells and how it affects the overall transparency of outer shell; diagram h and i compares the bloom of pigments in krill skin versus that of the optofluidic cell designed by the researcher; diagram f and g illustrate what makes up a optofluidic cell; diagram e and j demonstrate how the control of pigment in the optofluidic cells are applied in the building surface.

This idea can be applied to buildings with static outer structures. Static outer layers cannot control the flow of light into the building. By deploying optofluidic cells, UV light doesn’t get directly through the building and fry up the structure.

The optofluidic cells consist of two sheets of plastic and one very thin layer of mineral oil sandwiched in between. When in use, a tube injects a small amount of water containing a pigment or dye, creating a bloom of color. When not in use, removing the water makes the bloom smaller. In other words, the windows look like regular windows when they don’t contain any pigment. However, in the presence of strong sunlight, the skyscraper changes color as each pigmented fluid is injected through tubes to keep itself cool.

“What we found is that our system could reduce the energy required for heating, cooling, and lighting by up to 30 percent compared with the other two options,” says Raphael Kay, master’s student at the University.

Hopefully in the future, we will see more buildings with shifting colors blooming in our communities!