We found a variety of microbial cells and their cellular components have hygroscopic behavior. By depositing these biomaterials on top of a humidity-inert film, a multi-layered bio-hybrid material is obtained, which can reversibly change shape and biofluorescence intensity in response to environmental humidity change. We characterized the performance of the film, which guide the design of a wearable running suit and a fluorescent shoe prototype. Those bio-flaps on wearables can dynamically modulate ventilation in synergy with the bodyâs need for cooling.
