A novel sensate 'string' for large-strain measurement at high temperature

The idea of designing a 'sensing string' is presented in this paper. This 'sensing string' is a hand-crocheted textile based strain sensor which can be used to measure the in-plane or out-of-plane large strain (up to 40%, which depends on the fabric structure) at high temperature (up to 400°C). The sensing mechanism is investigated theoretically by using a circuit network to analyse the key sensing elements contributing to the fabric sensor, and it is then validated experimentally to obtain the guidelines for the design of high performance strain sensors. It is found that the contact resistance between two contacting yarns is the key factor dominating the sensing mechanism. The fabric density, which determines the number of contacting points within a given length, is proved to be the most important factor governing the sensitivity, repeatability, hysteresis, linearity and strain range of the sensor. Temperature exhibits a greater effect on the magnitude of the initial resistance of the sensor.Institute of Textiles and Clothin