Achieving High Sensitivity, Ultra-Low Hysteresis, and High Stability: A Humidity Sensor Based on Imidazole Derivative-Polyaniline Composite

This research is focused on high-performance humidity sensor made by the drop-casting the solution of 3-(4,5-diphenyl-1H-imidazole-2-yl)phenol (DHIP) and polyaniline (PANI) between aluminum (Al) electrodes on a glass substrate. The synergistic interactions between the DHIP and PANI resulted in the formation of porous, rod-like structure with interconnected voids confirmed by the SEM images. The electronic device demonstrated a striking capacitive response in the humidity of 20%RH-95%RH. The capacitance was boosted from 13.5 pF to 75 pF at 120 Hz, while resistance was decreased from 59 MΩ to 7.6 MΩ. The conduction mechanism of the fabricated sensor was based on von Grotthuss hydroxide (HO - ) ions transfer and H + ions mobility. The von Grotthuss hopping process controlled the efficient transfer of these ions in multi-physisorbed water layers. The sensor showed competitive response/recovery time of 50 s and 40 s, respectively. Moreover, the sensor showed excellent linearity in both mono-chemisorbed and multi-physisorbed regions (with R ² = 0.93 and 0.99), low hysteresis (≤ 4.51%), high sensitivity (up to 455.6% at 120 Hz), and long-term stability. These superior features of comparatively fast dynamics, low hysteresis loss, and reproducibility highlight the potential of DHIP–PANI composites as robust materials for next-generation humidity sensing technologies applicable to environmental monitoring, healthcare, and industrial process control.