Thermally Drawn Super‐Elastic Multifunctional Fiber Sensor for Human Movement Monitoring and Joule Heating

Abstract With the increasing demand of smart electronic textiles, fiber‐shaped sensing devices have rapidly attracted growing interests, in which elastic fiber sensors can monitor a wider range of strains without compromising their flexibility and adaptability with conventional textiles. However, it is still a major challenge to prepare highly sensitive and durable sensing fibers with multifunction. Herein, using a thermally drawn process, highly stretchable elastomeric fibers that are composited with copper particle‐mixed liquid metal electrodes to produce highly elastic piezoresistive strain sensor are fabricated. The composite liquid medal fiber sensor (LMFS) exhibits a strain at break up to 850% and a tensile stress of 6 MPa. When used as a tensile sensor, LMFS can detect large strain levels up to 400%. As a pressure sensor, LMFS can detect an object as light as 0.2 N. The composite fibers can be integrated into a fabric to monitor human motions and Morse code signals. In addition, the fibers can also be applied as an electric heater, the temperature quickly reaches 45 °C at 0.6 V in its original length and 29.3 °C at 0.6 A current with a 250% strain. This work exhibits excellent potential of multifunctional fiber devices in wearable sensing devices.