A novel large-area embroidered temperature sensor based on an innovative hybrid resistive thread

Abstract This study introduces a novel large-area embroidered temperature sensor based on an innovative hybrid resistive thread. The hybrid thread is composed of strands containing polyester fibers and one resistive stainless steel microwire. The sensor itself is embroidered as a helical meander-shaped structure into the carrier fabric and is intended mainly for smart protective clothing used by firefighters or other professionals to provide them protection against thermal risk, such as heat, fire or burn injury. The capabilities of the hybrid resistive thread are demonstrated through tests on the thread’s resistance to the washing/drying process. The properties of the sensor element are verified through the results of temperature calibration performed in the temperature range from 40 °C to 120 °C and the results of measurements performed in a thermal shock chamber, where sensor specimens were subjected to rapid temperature cycling between the temperatures of −40 °C and 125 °C. The observations are supported by the results of measuring the long-term thermal stability of the sensor at an elevated temperature of 125 °C for 1000 h. The hybrid resistive thread is shown to have acceptable mechanical resistance to the washing/drying process. The sensor was observed to have a fast time response to sudden temperature changes. Temperature calibration revealed the linear dependence between the electrical resistance and temperature throughout the evaluated temperature range. The calculated values of the temperature coefficient of resistance and the sensor sensitivity, together with the results obtained from the long-term thermal stability measurement, have also proven the suitability of the sensor for the targeted applications.