ZnO-CuO nanomaterials based efficient multi-functional sensor for simultaneous detection of humidity and mechanical pressure

Abstract Designing of materials is a critical factor for sensitive, stable and practically applicable humidity sensor, herein we report synthesis of ZnO-CuO mixed oxide nanoparticles and their fabrication into nanocomposite with silicon adhesive as a cost-effective humidity sensor with reliable sensitivity and stability. Between the gap of pre-fixed copper electrodes on the glassy substrate, the prepared binary oxides nanoparticles of ZnO-CuO and its silicon adhesive nanocomposites were deposited for relative humidity (RH) and mechanical pressure detection as multimodal sensor. The fabricated sensor was utilized for sensing assessment of humidity and pressure which responded in impedimetric measurements of relative humidity and pressure. The impedance of the pristine mixed oxides of ZnO-CuO decreased 35 times as relative humidity increased from 10-90% RH while 24 times decrease was observed in nanocomposite sample. Capacitances increased by a factor of 125 in pristine mixed oxides of ZnO-CuO and 80 times in nanocomposite at 100 Hz working frequency with the relative humidity (RH) increase in 10 to 90% RH range. The impedance of the sensors displayed strong dependence on the mechanical pressure as well. Similarly, the impedance of the material decreased in pristine samples by 3.8 times when a mechanical pressure of 11.0 KN/m 2 was applied on the fabricated sensor while capacitance in pristine samples increased by 4.61 times at the same pressure. In the composite samples impedance decreased 1.38 times and capacitance increased under effect of the pressure accordingly on 1.47 times.