Ultrahigh-responsive non-contact MXene-based flexible sensor: From real-time humidity sensing to smart healthcare applications

With excellent conductivity, large specific surface area, and tunable surface properties, MXene is regarded as a promising material for research in humidity sensing technologies. Nevertheless, achieving the high response intensity, excellent response sensitivity, structural stability, and oxidation resistance in the MXene-based humidity sensors remains a formidable challenge. Herein, this work presents a NiFe layered double hydroxide modified MXene composite material as the humidity sensing material with superior sensing performance. By adding the composite material to the carboxymethyl cellulose solution, a humidity-sensitive functional ink was prepared with favorable printability. Besides, the screen-printing process was successfully adapted to prepare the mass-producible humidity sensor. Experimental results indicate that the humidity sensor in this research possesses exceptional sensitivity (1.10 s/7.89 s for response/recovery time) and satisfactory response intensity (90,843% at 97% RH), along with favorable physicochemical stability and functional durability. Eventually, the function of the humidity sensor for skin humidity sensing, real-time respiration monitoring, soil moisture, and temperature visualization has been evaluated, revealing significant potential in meteorological monitoring, industrial production, intelligent home, and personalized healthcare management.