Impedimetric humidity and temperature sensing properties of chitosan-CuMn2O4 spinel nanocomposite

Abstract

Chitosan and CuMn2O4-spinel nanopowder were used to develop organic-inorganic nanocomposites based impedimetric humidity and temperature sensors. The CuMn2O4 nanopowder was synthesized using low temperature stirring technique. The average size of the synthesized nanoparticles was around 50 nm. Mechanical mixing (eco-friendly) technique was used to develop nanocomposite of CuMn2O4 spinel nanopowder and chitosan with 1:3 by weight. Hydraulic press was used to make Pellet of thickness 1 ± 0.1 mm and diameter 10 mm under the pressure of 187–437 MPa. The electrodes of 10 mm length were deposited by using silver paste. Sensing mechanism of the fabricated temperature and humidity sensors is based on variation in impedance with change in temperature and humidity, respectively. The rates of change of impedance with change in temperature and humidity are up to −347.5 kΩ/°C and −263.9 kΩ/%RH, correspondingly. The response and recovery times of the humidity sensor are 20s and 47s, respectively. Sensing range of temperature sensors is 21 °C–80 °C, while that of humidity sensors is 22 %RH to 94 %RH. It was found that the optimum pressure for the fabrication of temperature and humidity sensors are 312 MPa and 187 MPa, respectively. The fabricated sensors can be preferentially applied as a sensing elements in a variety of environmental monitoring devices.