A multimodal impedimetric sensor for humidity and mechanical pressure using a nanosized SnO2-Mn3O4 mixed oxide

The authors describe a sensor based on the deposition of the binary oxide SnO2-Mn3O4 between copper electrodes fixed on a glass substrate. The impedance of the sensor is shown to strongly depend on relative humidity ( RH) and mechanical pressure. A silicone adhesive was added to the binary oxide nanomaterials and investigated with respect to its effect on the sensing performance. The impedance of the material decreases by a factor of 54.7 with increasing RH in the range of 10-90% in pristine SnO2-Mn3O4 nanorods, but 29.6 times in SnO2-Mn3O4 nanocomposites. Capacitance increases 390 times in pristine SnO2-Mn3O4 and 26.6 times in SnO2-Mn3O4 silicone nanocomposite at 100 Hz on going from 10 to 90% RH. Similarly, the impedance of the sensor also depends on mechanical pressure. The impedance of the material decreases by 80% on applying a mechanical pressure of 11.0 kN.m(-2), while capacitance increases by 70% at the same pressure.