Efficient Fabrication of CrFeO₃‐Based Humidity Sensing Device with Fast Dynamics for Real‐Time Breath Monitoring and Contact‐Less Sensing

Abstract

In this study, a simple and cost‐effective method is presented for developing a metal oxide‐based humidity sensor. CrFeO3 is synthesized without any precipitating agent and chosen as a model material to study the validity of humidity sensing properties. The surface morphology and structural analysis are provided using field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. Elemental analysis is provided with the help of X‐ray photoelectron spectroscopy (XPS). Obtained results demonstrate the tunable response of order 860 and stability in a large range of humidity. Also, by controlling the porosity and film uniformity, a fast response time of 1.6 s and a recovery time of 2.6 s are achieved with very low hysteresis. Also, cole–cole plot and Fourier transform infrared spectroscopy (FTIR) spectra in the presence and absence of humidity provide detailed analysis of surface interaction with H2O molecules. In addition to this, the developed sensor demonstrates excellent response and reproducibility toward real‐time human respiration monitoring along with non‐contact sensing. This work enables the study of developed sensors in real‐time humidity monitoring for practical applications.