The development of strain sensors featuring both ultra high sensitivity and high stretchability is still a challenge. We demonstrate that strain sensors based on fragmented single-walled carbon nanotube (SWCNT) paper embedded in poly(dimethylsiloxane) (PDMS) can sustain their sensitivity even at very high strain levels (with a gauge factor of over 10 at 50% strain). This record sensitivity is ascribed to the low initial electrical resistance (5-28 Ω) of the SWCNT paper and the wide change in resistance (up to 10 Ω) governed by the percolated network of SWCNT in the cracked region. The sensor response remains nearly unchanged after 10 000 strain cycles at 20% proving the robustness of this technology. This fragmentation based sensing system brings opportunities to engineer highly sensitive stretchable sensors.

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CitationHigh-ampacity conductive polymer microfibers as fast response wearable heaters and electromechanical actuators 2016, 4 (6) Conductive fibers with enhanced physical properties and functionalities are needed for a diversity of electronic devices. Here, we report very high performance in the thermal and mechanical response of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) microfibers when subjected to an electrical current. These fibers were made by combining hot-drawing assisted wetspinning process with ethylene glycol doping/de-doping can work at a high current density as high as 1.8 ⇥ 10 4 A cm 2 , which is comparable to that of carbon nanotube fibers. Their electrothermal response was investigated using optical sensors and verified to be as fast as 63 C s 1 and is comparable with that of metallic heating elements (20-50 C s 1 ). We investigated the electromechanical actuation resulted from the reversible sorption/desorption of moisture controlled by electro-induced heating.Results revealed an improvement of several orders of magnitudes compared to other linear conductive polymer-based actuators in air. Specifically, the fibers we designed here have a rapid stress generation rate (> 40 MPa s 1 ) and a wide operating frequency range (up to 40 Hz). These fibers have several characteristics including fast response, low-driven voltage, good repeatability, long cycle life and high energy efficiency, favoring their use as heating elements on wearable textiles and as artificial muscles for robotics.

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