Graphene-based electronic textile sheet for highly sensitive detection of NO2 and NH3

Graphene-based electronic textiles (e-textiles) have generally fabricated with one-dimensional (1D) textile (e.g., yarn) to serve as wearable devices or smart textiles for detecting hazardous gases. For an improved sensing performance, flexible 1D e-textile yarns can be woven and patterned to form two-dimensional (2D) sheets; however, these sheets suffer from batch-to-batch variations while manufacturing by hand. To address these issues, we fabricated a graphene-based electronic sheet (GES) on a polyester sheet with a uniform grid fishnet pattern. The 2D GES exhibited high conductance (similar to 7 mu S) and sensitivity toward NO2 (0.34 mu A/ppm) and NH3 (0.16 mu A/ppm), which are indicative of a significantly improved performance as compared to that of the 1D etextile yarn. Furthermore, the 2D GES not only exhibited an improved NO2 sensing response that was approximately three times higher than that of the 1D e-textile yarn but also showed other advantages, such as being 19 times lighter and 5 times thinner per unit area. Moreover, we confirmed that the GES enabled the detection of not only NO2, which is emitted from vehicle exhausts but also the NH3 present in the atmosphere and artificial breath. We also found that the GES possessed high mechanical flexibility to endure a 1,000-cycle bending test. These results suggest that the GES could be a next-generation 2D wearable gas sensor for detecting toxic environmental gases and monitoring health by exhalation.