TEXTILE BASED TEMPERATURE SENSOR WITH HIGH STABILITY AGAINST HUMIDITY

In this study, the behavior of textile-based temperature sensors developed by inkjet printing technique in different humidity environments was investigated. Carbon nanotube (CNT), Poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS), and CNT/PEDOT:PSS composites were used as temperature sensitive materials. Performance comparison of three different types of sensors was discussed. To evaluate the sensor sensitivity, the electrical resistance of the sensors was measured at temperatures ranging from 25 to 50 ^oC and under 65% and 85% relative humidity. Experimental results show that the sensor resistance can vary depending on the relative humidity and the selected material properties. Although the lowest measurement sensitivity in different humidity environments is in the CNT ink printed sensor, when the relative humidity rises from 65% to 85%, the change in temperature resistance coefficient (TCR, a) was found to be higher compared to the CNT/PEDOT: PSS composite ink printed sensor. The temperature sensor that exhibits the best stability to the change against 65-85% relative humidity is found to be CNT/ PEDOT: PSS composite ink printed temperature sensor (TCR change = 0.02 ° C ^-1). Therefore, it is more suitable to use CNT/ PEDOT: PSS composite ink printed temperature sensor for temperature sensor applications where the environmental conditions include 65-85% relative humidity. In general, it is concluded that temperature sensors containing CNT are less affected by humidity than temperature sensors containing PEDOT: PSS.