Urea modified Cu-doped LaFeO3 nano-particles for humidity sensing with contactless moisture detection for medical and agricultural application

Nowadays, the role of humidity is a major factor in numerous applications such as medical purposes and soil moisture detection. In this work, we synthesized pristine LaFeO₃ (LFO1, LFO2) nanoparticles via hydrothermal method with and without urea. Furthermore, the synthesis of LFO doped with Cr, Cu and Mn was also done in the presence of urea using hydrothermal technique and studied for humidity sensing. The XRD confirms the crystalline size of the developed nanoparticles ranges in 19–25 nm. The sensing properties of pristine and doped LFO sensors for humidity sensing have been investigated in the 11 % – 90 % relative humidity (RH) range. As compared with others, the Cu-doped LFO sensor exhibits better response and recovery time of 5.4 s and 3.8 s respectively. Additionally, the nanoparticles of Cu-doped LFO show a highly porous nature having nano-perforated dumbbell structure as identified from the FESEM images. Moreover, to check the functionality of the developed sensor, the device is fabricated, resulting in the linear increase in output current with increase in relative humidity at a bias voltage of 1 V. With rapid response and recovery time, superior sensitivity and long-time stability, the developed Cu-doped LFO sensor can be used for medical detection of asthma, apnea and cough, as well as for non-contact skin monitoring that indicates its potential use to identify the moisturizing products for skin care. Finally, the efficacy of the fabricated sensor to monitor real-time humidity is also observed via IoT on a laptop/smartphone to display its potential to detect soil moisture for agriculture application.