Flexible and Highly Sensitive Humidity Sensor Based\non Cellulose Nanofibers and Carbon Nanotube Composite Film

Abstract

Flexible\nand highly sensitive humidity sensors are crucial for\nhumidity detection. In this study, a flexible cellulose nanofiber/carbon\nnanotube (NFC/CNT) humidity sensor with high sensitivity performance\nwas developed via fast vacuum filtration. CNTs were well dispersed\nin water by using 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized\nNFC as a dispersant. More importantly, NFC also acted as a humidity\nsensitive material, achieving superior performance of NFC/CNT humidity\nsensors. The obtained NFC/CNT humidity sensor with 5 wt % CNT loading\nexhibits outstanding sensitive performance, and its response value\nreaches a maximum of 69.9% (Δ<i>I</i>/<i>I</i>₀) at 95% relative humidity (RH). It also displays good\nbending resistance and long-term stability. In addition, the NFC/CNT\nhumidity sensor was employed to monitor human breath. Therefore, we\nbelieve that the flexible, highly sensitive, and simply designed NFC/CNT\nhumidity sensor is a promising candidate for various applications\nin the field of humidity measurement.