Electrospun Lignin/ZnO Nanofibrous Membranes for Self-Powered Ultrasensitive Flexible Airflow Sensor and Wearable Device

The interest and demand for flexible sensors and wearable devices are rapidly growing. The added benefit of electricity generation, enabling gas sensors to be self-powered, increases the applicability of these devices for flexible and wearable airflow sensors. Inspired by water evaporation-induced power generation, this study explores its potential in sensing applications, which has not yet been explored in detail. Electrospinning technology is used to prepare superhydrophilic lignin/ZnO nanofibrous membranes with a ZnO nanoparticle layer, capable of generating at least 100 mV (which allows it to power its own signal transduction). The membrane is highly sensitive to variations in airflow, enabling its use as an ultrasensitive and flexible airflow sensor. This sensor demonstrates exceptional performance, including a fast response time (0.65 s), broad detection range (with lower detection limit down to 0.25 and upper detection limit of 3 m s⁻¹), and extremely high airflow velocity detection accuracy. Beyond these, it can serve as a wearable sensor for sweat monitoring, motion detection, and breath monitoring (to accurately detect breathing rate, intensity and variations in speech). Such self-powered, ultrasensitive, and flexible lignin/ZnO airflow sensors provide novel potential to advance the development of smart textiles and wearable electronics.