Silk Fibroin-Based Wearable All-Fiber Multifunctional Sensor for Smart Clothing

Wearable sensing technology enables the interaction between the physical world and the digital world, as takes an irreplaceable role in development of the Internet of Things (IoT), and artificial intelligence (AI). However, increasing requirements posed by rapid development of wearable electronic information technology bring about many for wearable sensing technology, such as the demands for ultrahigh flexibility, air permeability, excellent biocompatibility, and multifunctional integration. Herein, we propose a wearable all-fiber multifunctional sensor (AFMS) based on a biocompatible material, i.e., silk fibroin. A simple two-layer configuration of a silk fiber film and an interdigital Ag nanowires (AgNWs) electrode was designed to construct the AFMS, in which silk fibroin simultaneously serves as a fundamental supporting component and a functional sensing component. Electrospinning and spray coating technologies were introduced to process the silk fiber film and the AgNWs electrode. The all-fiber configuration allows AFMS to possess ultrahigh flexibility and good air permeability, and silk fibroin enables the AFMS to have excellent biocompatibility. More importantly, benefiting from the all-fiber structure and the environmentally sensitive dielectric property of silk fibroin, the AFMS presented multiple sensing characteristics, including pressure sensing, temperature sensing, and humidity sensing. Among them, the pressure sensing function reached a high sensitivity of 2.27 pF/kPa (7.5%/kPa) and a remarkable resolution of ~ 26 Pa in the low pressure range. Additionally, the outstanding mechanical reliability and sensing stability of AFMS were proven by a systematic experiment. In addition, the AFMS was successfully applied for smart mask for breathing monitoring and a smart glove for bending angle recognition of finger joints. Multiple sensing characteristics combined with prominent fundamental features enable the AFMS tremendous potential in the smart sensing field, e.g., smart clothing. Graphical abstract