Electric properties of the ITO-orange dye-CNT-rubber cell-based flexible multifunctional sensors

Fabricated multifunctional sensors have the following structure: the flexible transparent conductive sheet as the first electrode, the orange dye as sensitive material and the CNT film as second electrode deposited on the flexible rubber substrate by rubbing-in technology. The samples (ITO/OD/CNT/Rubber) were investigated under the effects of displacement, pressure, temperature, relative humidity and infrared irradiation (IR). It was observed that under the effect of 25-mu m displacement, the resistance and the impedances at 100 Hz, 1 kHz and 10 kHz decreased by 1.62, 1.34, 1.26 and 1.23 times, accordingly. Under the effect of pressure up to 47 gf/cm(2), the resistance and impedances at 100 Hz, 1 kHz and 10 kHz decreased, respectively, by 1.35, 1.34, 1.32 and 1.29 times. The illumination of the samples by infrared irradiations of intensity up to 4830 W/m(2) brings to decrease the resistance and impedances up to 5 and 2 times, accordingly. By investigating temperature dependences of the impedances, it was found that the temperature coefficients of the impedances for frequencies of 100 Hz, 1 kHz and 10 kHz were equal to 0.037, 0.036 and 0.035 degrees C-1, respectively. The change in impedance/resistance with variation in the displacement, pressure, temperature and infrared irradiation may be explained by percolation theory. Investigation of humidity effect on the impedances of sensor showed that the decreased impedances (on increasing humidity) can be estimated by the humidity coefficients of impedance, which were equal to 0.020, 0.0190 and 0.014 RH-1 for the frequencies of 100 Hz, 1 kHz and 10 kHz. The investigation of frequency response showed that the samples are high-pass filter with cutoff frequency of 100 Hz. The fabricated devices may be implemented for various industrial and environmental applications.

Automated summary

Fabricated multifunctional sensors exhibit different variations in resistance and impedance under the effects of displacement, pressure, temperature, humidity, and infrared irradiation, which can be explained by percolation theory. The impedance of the sensors is influenced by humidity and acts as a high-pass filter, suitable for various industrial and environmental applications.