Intense exercise or exposure to direct sunlight in a hot and humid environment can cause continuous accumulation of heat on the body surface, leading to excessive sweating in the human body. In severe cases, it can cause imbalance in the body's temperature regulation and result in heat stress. Therefore, personal thermal and humidity regulation technology based on fiber materials has emerged. Utilizing the principle of biomimicry to simulate the relationship between biological functions and structures is considered a promising method for designing temperature-regulating fibers and fabrics. It can better meet individual needs, have good adaptability to various environments, and achieve rapid drying and cooling of the human microenvironment. 
Bio-inspired moisture-absorbing and sweat-evaporating cooling fibers and fabrics
There are various forms of water and moisture conducting methods in nature. For instance, the micro-convex structures and three-dimensional waxy tube structures on the surface of lotus leaves result in a very small contact area between water droplets and the lotus leaf, exhibiting superhydrophobic properties. The wings of butterflies have similar ratchet-like scales, which can form an anisotropic superhydrophobic surface, causing water droplets to detach from the butterfly's body surface. The droplets can easily roll off the wing surface along the radial direction from the center axis of the body. 
The researchers used double-ply polypropylene yarn as the surface yarn and polypropylene yarn wrapped with spandex as the ground yarn to develop a biomimetic fabric with a structure similar to butterfly scales. When worn during exercise, it showed good thermal and moisture comfort performance. Inspired by the water absorption of waterbird beaks, some researchers prepared a hydrophobic/hyperhydrophilic Janus polyester/cellulose nitrate fabric. Its inner surface was embedded with a cone-shaped microporous array with a hydrophilic inner surface, which could achieve directional liquid transportation (with an extremely high directional water transport capacity of 1246%) and maintain normal body temperature (2 - 3 ℃ higher than cotton textiles). 
Bio-inspired radiation-cooling fibers 
Natural organisms often have their own unique ways of cooling down. The cocoon of silkworms can protect the silkworm pupae from rapid temperature fluctuations by randomly stacking its silk. These stacked silks perform thermal regulation by reflecting sunlight and heat radiation. Inspired by the cooling mechanism of the silkworm cocoon, researchers used meltblown technology to prepare a random-stacked meltblown polypropylene fiber membrane (MB-PP), and built a polydimethylsiloxane film on it to increase the thermal emissivity of MB-PP. The surface-modified MBPP (SMB-PP) achieved a solar reflectance of approximately 95% and a thermal emissivity of 0.82. It could reduce the ambient temperature by 4 ℃ during the day and 5 ℃ at night. 
Inspired by the synergistic thermal optical effect of polar bear fur, researchers used the freeze-drying method to prepare porous polyethylene aerogel layers and laminated them onto a PDMS film, developing a flexible, superhydrophobic and reusable double-layer cooling material that mimics polar bear fur. Due to the low thermal conductivity of polyethylene aerogel (0.032 W/(m·K)), the heat on the PDMS film side mainly dissipates through conduction and radiation through the polyethylene gel. The apparent temperature of the PDMS film surface tested at noon was 5 to 6 degrees Celsius lower than the ambient temperature. Under ideal usage conditions, the estimated maximum cooling value can reach 14 degrees Celsius.