Sweat-activated winter jacket improves body heat control by 82.8%

A team of scientists led by Xiuqiang Li at Nanjing University of Aeronautics and Astronautics has developed a sweat-activated winter jacket that significantly improves thermal regulation by up to 82.8% compared to traditional textiles. The jacket uses a bacterial cellulose membrane as its filling, which automatically adjusts its thickness based on humidity levels: it remains thick (13 millimeters) in dry, cold air to retain warmth and shrinks to 2 millimeters when humidity rises from sweating, allowing better cooling during physical activity. This adaptive feature helps maintain comfort by preventing overheating without sacrificing insulation. The membrane was tested both in controlled lab settings, using a system simulating human skin, and in real-world trials where volunteers wore the jacket while walking or cycling outdoors. Results showed the jacket could extend the “no-thermal stress zone” by an average of 7.5 hours across 20 cities, making it particularly beneficial for outdoor workers such as sanitation staff, couriers, and police