The ability of the squid and other organisms to change skin color for thermoregulation and camouflage spurred University of Toronto engineers to mimic this function in pursuit of reduced building energy use. The result is a multi-layered fluidic system designed to lower energy costs of HVAC and lighting in buildings by optimizing the wavelength, intensity and dispersion of light.

Compared with automatic blinds, electrochromic windows and other existing technologies, the optofluidic solution described in the journal PNAS offers greater control while keeping costs low due to its use of simple, off-the-shelf components. The microfluidic system is composed of flat sheets of plastic filled with an array of millimeter-thick channels to accommodate fluid pumping. Customized pigments, particles or other molecules can be mixed into the fluids to control what kind of light gets through and in which direction the light is distributed.

The sheets can be assembled in a multi-layer stack, with each layer responsible for a different type of optical function: controlling the intensity, filtering the wavelength or tuning the scattering of transmitted light indoors. The system can reportedly optimize light transmission with small, digitally controlled pumps to add or remove fluids from each layer.

Simulations demonstrated that fluid-based scattering could reduce electric lighting consumption by 10%, and control over total absorption and near infrared — selective absorption could reduce heating and cooling energy by 51% and 25%, respectively, for a standard space in Toronto. Dynamically optimized combinations of system layers and components offer scope to outperform a state-of-the-art electrochromic window by 43%

The researchers are working to scale up the optofluidic system for future incorporation into building facades.