Three-dimensional interconnected nanofiber network derived from bacterial cellulose for strain sensing and energy harvesting

Abstract

Flexible strain sensors have garnered widespread attention due to their potential applications, including human health monitoring, human-machine interfaces and intelligent robotics. However, the tradeoff between sensitivity and detection range needs to be considered. Herein, a dual-functional film based on bacterial cellulose is fabricated with a cost-effective freeze-drying and carbonization process, which is used for strain sensing and energy harvesting. The effect of the carbonization temperature on the structure is explored. Taking advantage of three-dimensional interconnected nanofiber of carbonized bacterial cellulose (CBC) network and the stretchability of the Ecoflex substrate, the optimized sensor demonstrates impressive strain sensing capabilities, featuring exceptional sensitivity (gauge factor = 100), large tolerable strain (100 %), swift response time (70 ms), and robust durability (3000 cycles). These features endow the CBC strain sensor with the capability to effectively discern and monitor multiple complex human activities, such as pulse rate and various human movements. Moreover, the CBC structure can serve as triboelectric nanogenerator (TENG) for energy harvesting. This work provides a green, efficient and cost-effective manufacturing method for the development of multifaceted wearable devices for human health monitoring and portable energy sources.