Effect of chemical treatment and intrinsic resistance on the humidity sensitivity of pencil graphite sensing material coated on paper substrate

In this study, we have demonstrated the humidity sensitivity of graphite pencil marks sensing material drawn on paper. The fabricated sensing devices (sensors) were characterized for their humidity sensitivity by measuring the resistance changes across the pencil marks. In order to improve the humidity sensitivity of the sensing material, ethanol chemical treatment was applied on the pencil marks to increase their surface hydrophilicity. Sensors with different levels of intrinsic resistances were also prepared and tested. Results showed that the ethanol-treated sensors have better humidity sensitivities and the intrinsic resistances of the sensors were directly proportional to their humidity sensitivity. To evaluate this carbonbased sensing material, the humidity sensing characteristics of the pencil graphite were gauged with other forms of carbon materials that have been reported in previous studies, such as carbon quantum dots film, carbon nanoparticles, carbon nanotubes, graphene oxide and graphene. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, the humidity sensitivity of graphite pencil marks on paper as sensing material was demonstrated, with ethanol treatment improving the sensitivity. Sensors with different resistances were tested, showing that ethanol-treated sensors had better sensitivity proportional to their resistance. Comparison with other carbon materials like carbon quantum dots film, carbon nanoparticles, carbon nanotubes, graphene oxide and graphene was also conducted for evaluation.