Liquid-Gated Transistors Based on Reduced Graphene Oxide for Flexible and Wearable Electronics

Graphene is regarded as the ultimate material for future flexible, highperformance, and wearable electronics. Herein, a novel, robust, all-green, highly reliable (yield ≥ 99%), and upscalable technology is reported for wearable applications comprising reduced graphene oxide (rGO) as the electroactive component in liquid-gated transistors (LGTs). rGO is a formidable material for future flexible and wearable applications due to its easy processability, excellent surface reactivity, and large-area coverage. A novel protocol is established toward the high-yield fabrication of flexible rGO LGTs combining high robustness (>1.5 h of continuous operation) with state-of-the-art performances, being similar to those of their rigid counterparts operated under liquid gating, including field-effect mobility of ≈10−1 cm2 V−1 s−1 and transconductance of ≈25 μS. Permeable membranes have been proven crucial to operate flexible LGTs under mechanical stress with reduced amounts of solution (<20 μL). Our rGO LGTs are operated in artificial sweat exploiting two different layouts based on lateral-flow paper fluidics. These approaches pave the road toward future real-time tracking of perspiration via a simple and cost-effective approach. The reported findings contribute to the robust and scalable production of novel graphene-based flexible devices, whose features fulfill the requirements of wearable electronics