Highly sensitive and superhydrophobic fabric sensor based on AgNPs/Polypyrrole composite conductive networks for body movement monitoring

Fabric sensors due to favorable flexibility and comfortability have remarkable progress in wearable sensing electronics recently, but it is enormous challenge to achieve broad sensing range, high sensitivity, stable sensing capability and great hydrophobicity for their practical applications. Herein, a highly sensitive and superhydrophobic strain sensor based on conductive polydimethylsiloxane/Ag nanoparticles/polypyrrole/nylon strip (PDMS/AgNPs/PPy/NS) is successfully fabricated via constructing AgNPs/PPy composite conductive networks on elastic NS, and then coating a thin protective layer (PDMS). The AgNPs/PPy composite conductive networks render the PDMS/AgNPs/PPy/NS large ΔR/R0 scale, and the assembled PDMS/AgNPs/PPy/NS strain sensor presents broad sensing range (0.1%–70%), high Gauge Factor value of 1.61 × 103 (with the strain range from 60% to 70%), ultralow detection limit (0.1% strain), fast response time (70 ms) and satisfying sensing stability (5000 cycles). The protective PDMS layer not only endows PDMS/AgNPs/PPy/NS strain sensor with excellent superhydrophobicity (WCA = 156°), but also improves the stability of sensor for daily use. Owing to the high sensitivity and excellent superhydrophobicity, PDMS/AgNPs/PPy/NS strain sensor can monitor various joint motions (throat, neck, elbow, wrist, knee and finger) and even work in harsh conditions (moisture, acid, alkaline and salt environment). In addition, PDMS/AgNPs/PPy/NS with low resistance (1.09 Ω cm−1) displays an outstanding electrothermal temperature (87.4 °C at 2.0 V). These remarkable performances demonstrate great potential of PDMS/AgNPs/PPy/NS in wearable electronics such as sensors and heaters.