A Nb₂CT_x/sodium alginate-based composite film with neuron-like network for self-powered humidity sensing

Existing wearable sensing electronics generally require to connect a battery for the power supply. Despite many years of effort, it still remains a great challenge to develop self-powered sensing systems without external power supplies. Herein, we develop a neuron-like MXene Nb₂CT_x/sodium alginate (Nb₂CT_x/SA) composite films prepared by an electrospinning approach. The Nb₂CT_x/SA composite film not only can be used to fabricate a high-performance electronic humidity sensor, but also to construct a moisture-triggered nanogenerator with a sustainable voltage output. Importantly, the humidity sensor is demonstrated to be portable and compatible for applications in respiration assessment, noncontact monitoring and intelligent alarm. More importantly, by simply integrating the Nb₂CT_x/SA film-based sensor/nanogenerator with a capacitor and light-emitting diode (LED), a prototype of self-powered sensing system capable of indicating different relative humidity (i.e., low, medium or high) through the LED's brightness without external power supplies is demonstrated. This work not only demonstrates the design and fabrication of a smart self-powered humidity sensing system, but also opens a new avenue for development of next-generation intelligent wearable electronics.