Stretchable conductive nonwoven fabrics with self-cleaning capability for tunable wearable strain sensor

With the fast growth of wearable intelligent devices, tunable strain sensors with broad strain sensing range and high sensitivity are in urgent demand. Furthermore, the merits of excellent waterproof property, self-cleaning, and anti-corrosion are also imperative for the practical applications of them. Herein, a tunable wearable micro-cracked non-woven fabrics (NWF) strain sensor with broad strain sensing range and high sensitivity was successfully developed based on the electrically conductive cellulose nanocrystal (CNC)/graphene (G) coating with controllable micro-crack density, which was achieved through changing the G loading of the coating layer, and its superhydrophobicity was achieved by simply dip-coating in the hydrophobic fumed silica (Hf-SiO2)/ethanol dispersion. As a result, a broad working range of 98% and GF value up to 2.36 × 104 are simultaneously achieved for the prepared strain sensor (G content is 25 wt%). In addition, it possesses an ultralow detection limit as low as 0.1%, short response time (33 ms) and good sensing stability over 1000 cycles. What's more, the NWF strain sensor presents excellent waterproofness (WCA = 154°), anti-corrosion ability, outstanding self-cleaning and stability. Due to the excellent response performances, the NWF strain sensor can successfully monitor various human activities from subtle deformations (e.g. speech recognition, pulse waves) to vigorous body movements (e.g. finger, elbow joint and wrist movement). Specially, owing to its excellent superhydrophobic characteristic, the strain sensor also exhibits superior self-cleaning capability and good applicability in a humid or underwater harsh outdoor environment.