On the contrary, the chemical reactions necessary for life, and more particularly the metabolisms of each living being, are efficient within restricted temperature ranges, whereas external temperatures, in the air or in the water, vary enormously within a day, a year, or even geographically.

It's no coincidence that migratory birds fly to warmer climes in winter! Animals that overwinter or hibernate have chosen a different strategy to combat the cold: since it makes them less efficient, they work less. Numerous other mechanisms are employed by all species to adapt their temperature, as always in nature, in the most energy-efficient way possible.

Thus, furs or feathers insulate the animals that wear them, perspiration cools both plants and animals, and nests or burrows provide protection against outside temperatures.

Finally, individual or collective behaviors also play an essential role in animal thermoregulation.

Silver ants live in the Sahara Desert. They must protect themselves from the arid conditions there: their body temperature must remain between 48°C and 51°C, while under the sun the ground temperature can exceed 70°C!

Unlike many species in hot deserts, their strategy isn't to be nocturnal and hide during the day. How do they survive such temperatures? Their hairs provide excellent protection. Thanks to their triangular shape, they reflect most of the sunlight they receive, thus limiting the heat from the sun. It's this reflection that gives these ants their beautiful silvery color!

In addition, the microstructure of these hairs allows for good emissivity of infrared radiation, which effectively cools the ant.

The structure of Saharan ant hairs has been replicated to create a surface with cooling properties. This new surface reflects more than 97% of solar radiation, greatly limiting its heating.

Furthermore, the structure, similar to that of silver ant hairs, enhances the surface's emissivity, allowing it to cool more efficiently through radiation. The resulting cooling power is the highest achieved to date for a microstructure, opening up promising possibilities for thermoregulation, whether for buildings or even satellites.

Polar bears are subjected to very low temperatures, which can reach as low as -40°C! As homeothermic animals, they manage to maintain a constant internal temperature in both summer and winter.

To help them with this, their fur provides excellent insulation: composed of numerous porous hairs, it creates a significant barrier between the bear and the outside world. Indeed, the air trapped in the fur conducts very little heat (this is what double glazing is used for!). In this way, the temperature difference between the outside of the fur, which remains very cold, and the inside, which must remain warm, is greatly amplified.

The surface of the polar bear then emits little infrared radiation, which limits the animal's heat loss through radiation.

An insulating textile has been developed using this structure. Composed of porous fibers, this textile is lightweight, durable, and thermally insulating. Like polar bear fur, it maintains a temperature difference between the outside and inside while also limiting the emission of thermal radiation. Among other applications, it can serve as an invisibility cloak for infrared cameras!

The human vascular system allows the transport within the body of nutrients for food and gases for respiration.

What is less well known is that it also plays a role in our thermoregulation. Indeed, the exchange of matter is accompanied by heat exchange, in order to maintain the core temperature at 37°C regardless of external conditions. The hierarchical organization of the blood vessel network, in which veins and arteries branch into increasingly numerous and smaller capillaries, allows for efficient exchange of matter and heat.

Microelectronic systems require efficient temperature control to prevent overheating. The ever-decreasing size of components necessitates continuous improvement of temperature control system efficiency. To address this, why not draw inspiration from our own body's thermoregulation? Thus, an algorithm has been developed to optimize the size and arrangement of channels in a heat exchanger, inspired by the vascular system. In the tested case, the resulting arrangement reduces the maximum temperature by 24°C compared to a conventional parallel channel configuration.