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 (∼7 μS) and sensitivity toward NO₂ (0.34 μA/ppm) and NH₃ (0.16 μA/ppm), which are indicative of a significantly improved performance as compared to that of the 1D e-textile 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.