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

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.