A Flexible Humidity Sensor Based on Natural Biocompatible Silk Fibroin Films

Abstract Incorporated biological materials into a flexible sensing platform, which possess the features of biocompatibility and a capability of humidity‐induced visual color changes, is of significant interest for environmental and health monitoring, anti‐counterfeiting, and stealth technologies. Here, it is reported on a transparent and flexible sensing device based on biocompatible, natural biomaterials silk fibroin (SF) films that display high humidity response, significant flexibility, and remarkable noncontact characteristics for detecting ambient and human health, such as exhaling, speech, and fingertip movement. Depending on the design of the bionic structure, the patterned SF films can be applied as a color humidity indicator with visual color changes, reversibility, and stability. Such versatility highlights the potential for applications in human activity detection, human–machine interface, anti‐counterfeiting, and optical humidity sensors.