title: Human-Finger Electronics Based on Opposing Humidity-Resistance Responses in Carbon Nanofilms.
abstract: Carbon nanomaterials have excellent humidity sensing properties. Here, it is demonstrated that multiwalled carbon-nanotube (MWCNT)- and reduced-graphene-oxide (rGO)-based conductive films have opposite humidity/electrical resistance responses: MWCNTs increase their electrical resistance (positive response) and rGOs decrease their electrical resistance (negative response). The authors propose a new phenomenology that describes a "net"-like model for MWCNT films and a "scale"-like model for rGO films to explain these behaviors based on contributions from junction resistances (at interparticle junctions) and intrinsic resistances (of the particles). This phenomenology is accordingly validated via a series of experiments, which complement more classical models based on proton conductivity. To explore the practical applications of the converse humidity/resistance responses, a humidity-insensitive MWCNT/rGO hybrid conductive films is developed, which has the potential to greatly improve the stability of carbon-based electrical device to humidity. The authors further investigate the application of such films to human-finger electronics by fabricating transparent flexible devices consisting of a polyethylene terephthalate substrate equipped with an MWCNT/rGO pattern for gesture recognition, and MWCNT/rGO/MWCNT or rGO/MWCNT/rGO patterns for 3D noncontact sensing, which will be complementary to existing 3D touch technology.
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Division of Physical Science and Engineering, COHMAS Laboratory, Thuwal, 23955-6900, Saudi Arabia.
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Tai
authors.affiliation: King Abdullah University of Science and Technology (KAUST), Division of Physical Science and Engineering, COHMAS Laboratory, Thuwal, 23955-6900, Saudi Arabia.
authors.forename: Gilles
authors.initials: G
authors.lastname: Lubineau
keywords: 3D noncontact sensing; carbon nanomaterials; gesture recognition; humidity-insensitive conductive films, touch technology