Desert Inspect Species Inspires “Cool” Coating

The thermodynamic figure compares the temperature of a Sahara silver ant head with and without hairs. The ant’s hair coating helps reduce body temperature substantially and serves as the inspiration for the “cool” coating developed by Nanfang Yu and his team. Image courtesy of Columbia Engineering.

Researchers from the Fu Foundation School of Engineering and Applied Science at Columbia University (Columbia Engineering) (New York, NY, USA), the University of Washington (Seattle, Washington, USA), and the University of Zürich (Zürich, Switzerland) have studied Saharan silver ants, an insect species able to stay cool in hot desert environments. The recent findings of these researchers have led to the development of a paint like material that mimics the ants’ ability to keep cool by reflecting sunlight and emitting heat back to the atmosphere. 

Led by Nanfang Yu, assistant professor of applied physics at Columbia Engineering, the research team has made two key discoveries about the Saharan silver ant. The first is that these ants have coats of uniquely shaped hairs with triangular cross-sections that both reflect sunlight and offload excess heat. Their second discovery is that the ants’ hair coating helps to reduce body temperature by 5 to 10 degrees without exceeding their critical thermal maximum of 53.6 °C (128.48 °F).

These factors aided researchers in learning how this ant species can maintain its heat-resistant abilities in the Sahara Desert, the largest hot desert in the world where midday surface temperatures reach up to 70 °C (158 °F). “Such biologically inspired cooling surfaces will have high reflectivity in the solar spectrum and high radiative efficiency in the thermal radiation spectrum,” says Yu. “So this may generate useful applications such as a cooling surface for vehicles, buildings, instruments, and even clothing.”

Yu and his team initially began this project back in 2015 to learn what role the silvery coats of Saharan silver ants played in keeping them cool. In the process, they discovered that their coats could control electromagnetic waves over a broad range of solar and thermal radiation spectrums. With this property in mind, the “cool” coating reflects up to up to 99% of sunlight when properly applied to a building or rooftop surface.

According to Yale Climate Connections, Yu claims that the coat is able to cool surfaces more effectively than white paint, which only reflects certain wavelengths of radiation, and can reduce high cooling and electrical costs. Yu adds that more research and testing needs to be done before this coating technology is made available for commercial use.

Source: Columbia Engineering, engineering.columbia.edu.